diff --git a/Mmake.common.in b/Mmake.common.in
index 3e4ce0960..0ad010134 100644
--- a/Mmake.common.in
+++ b/Mmake.common.in
@@ -219,6 +219,74 @@ include $(MERCURY_DIR)/Mercury.options
 $(MERCURY_DIR)/Mmake.params: ;
 
 #-----------------------------------------------------------------------------#
+#
+# `mmake check_namespace' performs various checks on the header files
+# and object files to make sure that they conform with our coding standards.
+#
+
+ifdef CHECK_OBJS
+
+HDR_CHECK_CS	  = $(CHECK_HDRS:.h=.check_hdr.c)
+HDR_CHECK_OBJS    = $(CHECK_HDRS:.h=.check_hdr.$O)
+HDR_CHECK_MACROS  = $(CHECK_HDRS:.h=.check.macros)
+MHDR_CHECK_CS	  = $(CHECK_MHDRS:.mh=.check_mhdr.c)
+MHDR_CHECK_OBJS   = $(CHECK_MHDRS:.mh=.check_mhdr.$O)
+MHDR_CHECK_MACROS = $(CHECK_MHDRS:.mh=.check.mmacros)
+OBJ_CHECKS        = $(CHECK_OBJS:%=%.obj_check)
+
+# Macro names must normally start with one of the prefixes associated
+# with the different components of our system:
+# 	`MR_' or `MERCURY_' for stuff in the Mercury runtime implementation
+# 		(the `runtime' and `trace' directories)
+# 	`ML_' for stuff in the Mercury standard library
+# 		(the `library' directory)
+# 	`MDB_' for stuff in the browser
+# 		(the `browser' directory)
+# 	`GC_' for stuff in the Boehm et al conservative garbage collector
+# 		(the `boehm_gc' directory)
+# 	`MPS_' or `mps_' for stuff in the Memory Pool System toolkit
+# 		(the `mps_gc' directory, if present -- note that this
+# 		is in a separate CVS module and is not included in the
+# 		normal Mercury source distributions)
+# Exceptions to this policy must be listed in the RESERVED_MACRO_NAMES file
+# in the relevant directory.
+
+GEN_MACRO_PREFIX_EXPRS = \
+	-e '^MR_' -e '^MERCURY_' -e '^GC_' -e '^MPS_' -e '^mps_'
+GEN_OBJ_PREFIX_EXPRS = \
+	-e '^MR_' -e '^_entry' -e '^mercury_'
+
+ifeq ("$(ALLOW_LIB_PREFIX)","yes")
+LIB_MACRO_PREFIX_EXPRS = \
+	-e '^ML_'
+LIB_OBJ_PREFIX_EXPRS = \
+	-e '^ML_'
+else
+LIB_MACRO_PREFIX_EXPRS =
+LIB_OBJ_PREFIX_EXPRS =
+endif
+
+ifeq ("$(ALLOW_BROWSER_PREFIX)","yes")
+BROWSER_MACRO_PREFIX_EXPRS = \
+	-e '^MDB_'
+BROWSER_OBJ_PREFIX_EXPRS = \
+	-e '^MDB_' -e '^mdb_'
+else
+BROWSER_MACRO_PREFIX_EXPRS =
+BROWSER_OBJ_PREFIX_EXPRS =
+endif
+
+MACRO_PREFIX_EXPRS = \
+	$(GEN_MACRO_PREFIX_EXPRS) \
+	$(LIB_MACRO_PREFIX_EXPRS) \
+	$(BROWSER_MACRO_PREFIX_EXPRS)
+OBJ_PREFIX_EXPRS   = \
+	$(GEN_OBJ_PREFIX_EXPRS) \
+	$(LIB_OBJ_PREFIX_EXPRS) \
+	$(BROWSER_OBJ_PREFIX_EXPRS)
+
+HEADER_CLEAN_FILTER = \
+	grep -v $(MACRO_PREFIX_EXPRS) | fgrep -v -x -f RESERVED_MACRO_NAMES
 
 # This rule checks that object files are properly namespace-clean, with
 # regard to the global symbols that they define.
@@ -228,39 +296,66 @@ $(MERCURY_DIR)/Mmake.params: ;
 
 %.obj_check: %
 	nm -g $< | awk '$$1 != "U" { print $$3; }' | \
-		grep -v -e '^_entry' -e '^MR_' -e '^mercury_' | \
-		sort -u > $@
+		grep -v $(OBJ_PREFIX_EXPRS) | sort -u > $@
 	@if cmp -s /dev/null $@; then \
 		true; \
 	else \
 		echo "** Global symbols in user namespace:"; \
 		cat $@; \
-		echo "(You may need to add MR_ prefixes to these names.)"; \
+		echo "(You may need to add a distinguishing prefix to these names.)"; \
 		exit 1; \
 	fi
 
-# This rule helps to check that header files is self-contained, i.e. that each
+# These rules help to check that header files is self-contained, i.e. that each
 # header file foo.h includes any other header files that define types
 # used by foo.h. It creates a foo.check_hdr.c file that contains only a single
 # `#include' statement that includes foo.h; compiling foo.check_hdr.c will fail
-# if foo.h is not self-contained.
+# if foo.h is not self-contained. Similarly for .mh files.
 
 %.check_hdr.c : %.h
 	echo "#include \"$*.h\"" > $*.check_hdr.c
 
-# This rule checks whether a header file defines any macros it shouldn't.
-# It generates the list of macros defined in the header file, and filters this
+%.check_mhdr.c : %.mh
+	echo "#include \"$*.mh\"" > $*.check_mhdr.c
+
+# These rules check whether a header file defines any macros it shouldn't.
+# They generates the list of macros defined in the header file, and filter this
 # list through a command that is intended to filter out all references to macro
-# names that are all right. Each directory that uses this rule must set
-# the HEADER_CLEAN_FILTER make variable to contain this command.
+# names that are all right. Each directory that uses this rule must set arrange
+# for the precursors of the HEADER_CLEAN_FILTER make variable to contain this
+# command.
+#
+# The two rules should differ only in the filenames they use and in the fact
+# that the automatically created header file for module x is allowed to have
+# two macros, X_H and X_DECL_GUARD over and above what HEADER_CLEAN_FILTER
+# allows.
 
 AWK = awk
+
 %.check.macros: %.h %.check_hdr.c
 	-$(MGNUC) $(ALL_GRADEFLAGS) $(ALL_MGNUCFLAGS) \
 		-DMERCURY_BOOTSTRAP_H -DMR_NO_CONF_BACKWARDS_COMPAT \
 		-E $*.check_hdr.c \
 		-nostdinc -dN \
-		2> /dev/null | $(AWK) '/^#define/ { print $$2; }' | \
+		2> /dev/null | $(AWK) '/[ \t]*#define/ { print $$2; }' | \
+		$(HEADER_CLEAN_FILTER) | sort -u > $@
+	@if cmp -s /dev/null $@; then \
+		true; \
+	else \
+		echo "** Macro name(s) in user namespace:"; \
+		cat $@; \
+		echo "(You may need to add a distinguishing prefix to these names.)"; \
+		exit 1; \
+	fi
+
+%.check.mmacros: %.mh %.check_mhdr.c
+	-$(MGNUC) $(ALL_GRADEFLAGS) $(ALL_MGNUCFLAGS) \
+		-DMERCURY_BOOTSTRAP_H -DMR_NO_CONF_BACKWARDS_COMPAT \
+		-E $*.check_mhdr.c \
+		-nostdinc -dN \
+		2> /dev/null | $(AWK) '/[ \t]*#define/ { print $$2; }' | \
+		grep -v -e `echo $(subst .check.mmacros,,$@) | tr '[a-z]' '[A-Z]'`_H | \
+		grep -v -e `echo $(subst .check.mmacros,,$@) | tr '[a-z]' '[A-Z]'`_DECL_GUARD | \
 		$(HEADER_CLEAN_FILTER) | sort -u > $@
 	@if cmp -s /dev/null $@; then \
 		true; \
@@ -272,3 +367,29 @@ AWK = awk
 	fi
 
 #-----------------------------------------------------------------------------#
+
+.PHONY: check_headers_self_contained
+check_headers_self_contained: $(HDR_CHECK_OBJS) $(MHDR_CHECK_OBJS)
+
+.PHONY: check_headers_macros
+check_headers_macros: $(HDR_CHECK_MACROS) $(MHDR_CHECK_MACROS)
+
+.PHONY: check_headers
+check_headers: check_headers_self_contained check_headers_macros
+
+.PHONY: check_objs
+check_objs: $(OBJ_CHECKS)
+
+.PHONY: check_namespace
+check_namespace: check_headers check_objs
+
+.PHONY: clean_check
+clean_check:
+	-rm -f $(HDR_CHECK_OBJS) $(HDR_CHECK_CS) $(HDR_CHECK_MACROS)
+	-rm -f $(MHDR_CHECK_OBJS) $(MHDR_CHECK_CS) $(MHDR_CHECK_MACROS)
+	-rm -f $(OBJ_CHECKS)
+
+endif
+# ifdef CHECK_OBJS
+
+#-----------------------------------------------------------------------------#
diff --git a/browser/Mmakefile b/browser/Mmakefile
index c603cc514..c7acb3001 100644
--- a/browser/Mmakefile
+++ b/browser/Mmakefile
@@ -15,6 +15,15 @@
 # in an executable must be of the same grade, we need to be able to
 # compile the modules in this directory in debug grades as well.
 
+# Specify which files to check for namespace cleanliness, and which name
+# prefixes are allowed.
+
+CHECK_HDRS  =
+CHECK_MHDRS = $(mer_browser.mhs)
+CHECK_OBJS  = $(mer_browser.os)
+ALLOW_LIB_PREFIX=yes
+ALLOW_BROWSER_PREFIX=yes
+
 MERCURY_DIR=..
 LINK_STDLIB_ONLY=yes
 include $(MERCURY_DIR)/Mmake.common
diff --git a/browser/RESERVED_MACRO_NAMES b/browser/RESERVED_MACRO_NAMES
new file mode 100644
index 000000000..e549bd601
--- /dev/null
+++ b/browser/RESERVED_MACRO_NAMES
@@ -0,0 +1,39 @@
+#-----------------------------------------------------------------------------#
+# Copyright (C) 2000-2002 The University of Melbourne.
+# This file may only be copied under the terms of the GNU General
+# Public License - see the file COPYING in the Mercury distribution.
+#-----------------------------------------------------------------------------#
+#
+# RESERVED_MACRO_NAMES
+#
+# This file lists the macro names, other than the ones starting with a
+# certain set of allowed prefixes that are defined by the Mercury header files.
+# The Mmakefile target `check_headers' automatically checks that no other
+# macro names are defined. This is done to keep our headers namespace-clean,
+# i.e. ensure that we don't invade the user's namespace.
+#
+# This file is used as the argument to `fgrep -f'.
+# Lines starting with `#' will not match anything in the input,
+# and can thus be used as comments.
+# Other lines are treated as strings to match against.
+#
+#-----------------------------------------------------------------------------#
+# This is documented in the Mercury language reference manual
+# and defined by mercury_types.h.
+SUCCESS_INDICATOR
+#-----------------------------------------------------------------------------#
+# pid_t is only defined in mercury_conf.h if it is not present
+# in the system headers. I don't think there is a nice way to
+# prefix this without requiring a later version of autoconf (e.g. 2.52).
+pid_t
+#-----------------------------------------------------------------------------#
+# These are defined by boehm_gc/gc.h.
+__GC
+_GC_H
+#-----------------------------------------------------------------------------#
+# This is defined by mps_gc/code/mercury_mps.h,
+# which uses this macro for its header guard.
+# Normally it would be better to use uppercase for header guard macro names,
+# but that would be inconsistent with the coding style used in mps_gc/code.
+mercury_mps_h
+#-----------------------------------------------------------------------------#
diff --git a/bytecode/Mmakefile b/bytecode/Mmakefile
index 855fbf878..497a70026 100644
--- a/bytecode/Mmakefile
+++ b/bytecode/Mmakefile
@@ -1,5 +1,5 @@
 #-----------------------------------------------------------------------------#
-# Copyright (C) 1998-2001 The University of Melbourne.
+# Copyright (C) 1998-2002 The University of Melbourne.
 # This file may only be copied under the terms of the GNU General
 # Public License - see the file COPYING in the Mercury distribution.
 #-----------------------------------------------------------------------------#
@@ -8,40 +8,6 @@
 
 MAIN_TARGET=all
 
-MERCURY_DIR=..
-include $(MERCURY_DIR)/Mmake.common
--include ../Mmake.params
-
-#-----------------------------------------------------------------------------#
-# NOTE: any library functions that called from bytecode must be compiled
-# with trace information. (So their entry labels can be looked up)
-#-----------------------------------------------------------------------------#
-
-MERCURY_SYSTEM	= \
-		$(RUNTIME_DIR)/*.c $(RUNTIME_DIR)/*.h \
-		$(RUNTIME_DIR)/machdeps/*.c $(RUNTIME_DIR)/machdeps/*.h\
-		$(LIBRARY_DIR)/*.m \
-		$(TRACE_DIR)/*.h $(TRACE_DIR)/*.c \
-		$(BROWSER_DIR)/*.h $(BROWSER_DIR)/*.c \
-		$(BOEHM_GC_DIR)/*.h $(BOEHM_GC_DIR)/include/*.h
-
-MERCURY_INC	= \
-		-I$(LIBRARY_DIR) \
-		 -I$(RUNTIME_DIR) \
-		 -I$(BOEHM_GC_DIR) \
-		 -I$(BOEHM_GC_DIR)/include \
-		 -I$(TRACE_DIR)
-	
-#-----------------------------------------------------------------------------#
-
-CFLAGS		= $(MERCURY_INC) -DMR_BYTECODE_CALLABLE -g
-
-MGNUCFLAGS-mb_disasm = --no-ansi
-
-MCFLAGS		= --trace shallow --generate-bytecode -O 0
-
-MLFLAGS		= --trace
-
 #-----------------------------------------------------------------------------#
 # keep these lists in alphabetical order, please
 
@@ -83,6 +49,48 @@ MB_OBJS		= $(MB_MFILES:%.m=%.o) $(MB_CFILES:%.c=%.o)
 
 $(MB_OBJS): $(MB_HDRS)
 
+# Specify which files to check for namespace cleanliness, and which name
+# prefixes are allowed.
+
+CHECK_HDRS  = $(MB_HDRS)
+CHECK_MHDRS =
+CHECK_OBJS  = $(MB_OBJS)
+ALLOW_LIB_PREFIX=no
+ALLOW_BROWSER_PREFIX=no
+
+MERCURY_DIR=..
+include $(MERCURY_DIR)/Mmake.common
+-include ../Mmake.params
+
+#-----------------------------------------------------------------------------#
+# NOTE: any library functions that called from bytecode must be compiled
+# with trace information. (So their entry labels can be looked up)
+#-----------------------------------------------------------------------------#
+
+MERCURY_SYSTEM	= \
+		$(RUNTIME_DIR)/*.c $(RUNTIME_DIR)/*.h \
+		$(RUNTIME_DIR)/machdeps/*.c $(RUNTIME_DIR)/machdeps/*.h\
+		$(LIBRARY_DIR)/*.m \
+		$(TRACE_DIR)/*.h $(TRACE_DIR)/*.c \
+		$(BROWSER_DIR)/*.h $(BROWSER_DIR)/*.c \
+		$(BOEHM_GC_DIR)/*.h $(BOEHM_GC_DIR)/include/*.h
+
+MERCURY_INC	= \
+		-I$(LIBRARY_DIR) \
+		 -I$(RUNTIME_DIR) \
+		 -I$(BOEHM_GC_DIR) \
+		 -I$(BOEHM_GC_DIR)/include \
+		 -I$(TRACE_DIR)
+	
+#-----------------------------------------------------------------------------#
+
+CFLAGS		= $(MERCURY_INC) -DMR_BYTECODE_CALLABLE -g
+
+MGNUCFLAGS-mb_disasm = --no-ansi
+
+MCFLAGS		= --trace shallow --generate-bytecode -O 0
+
+MLFLAGS		= --trace
 
 #-----------------------------------------------------------------------------#
 # The actual program (as distinct from bytecode interpreter)
diff --git a/library/Mmakefile b/library/Mmakefile
index 276c963a6..1f26e46be 100644
--- a/library/Mmakefile
+++ b/library/Mmakefile
@@ -13,7 +13,16 @@
 EXTRA_LDFLAGS =
 EXTRA_LDLIBS =
 #-----------------------------------------------------------------------------#
- 
+
+# Specify which files to check for namespace cleanliness, and which name
+# prefixes are allowed.
+
+CHECK_HDRS  =
+CHECK_MHDRS = $(mer_std.mhs)
+CHECK_OBJS  = $(mer_std.os)
+ALLOW_LIB_PREFIX=yes
+ALLOW_BROWSER_PREFIX=no
+
 MERCURY_DIR=..
 LINK_RUNTIME_ONLY=yes
 include $(MERCURY_DIR)/Mmake.common
diff --git a/library/RESERVED_MACRO_NAMES b/library/RESERVED_MACRO_NAMES
new file mode 100644
index 000000000..e549bd601
--- /dev/null
+++ b/library/RESERVED_MACRO_NAMES
@@ -0,0 +1,39 @@
+#-----------------------------------------------------------------------------#
+# Copyright (C) 2000-2002 The University of Melbourne.
+# This file may only be copied under the terms of the GNU General
+# Public License - see the file COPYING in the Mercury distribution.
+#-----------------------------------------------------------------------------#
+#
+# RESERVED_MACRO_NAMES
+#
+# This file lists the macro names, other than the ones starting with a
+# certain set of allowed prefixes that are defined by the Mercury header files.
+# The Mmakefile target `check_headers' automatically checks that no other
+# macro names are defined. This is done to keep our headers namespace-clean,
+# i.e. ensure that we don't invade the user's namespace.
+#
+# This file is used as the argument to `fgrep -f'.
+# Lines starting with `#' will not match anything in the input,
+# and can thus be used as comments.
+# Other lines are treated as strings to match against.
+#
+#-----------------------------------------------------------------------------#
+# This is documented in the Mercury language reference manual
+# and defined by mercury_types.h.
+SUCCESS_INDICATOR
+#-----------------------------------------------------------------------------#
+# pid_t is only defined in mercury_conf.h if it is not present
+# in the system headers. I don't think there is a nice way to
+# prefix this without requiring a later version of autoconf (e.g. 2.52).
+pid_t
+#-----------------------------------------------------------------------------#
+# These are defined by boehm_gc/gc.h.
+__GC
+_GC_H
+#-----------------------------------------------------------------------------#
+# This is defined by mps_gc/code/mercury_mps.h,
+# which uses this macro for its header guard.
+# Normally it would be better to use uppercase for header guard macro names,
+# but that would be inconsistent with the coding style used in mps_gc/code.
+mercury_mps_h
+#-----------------------------------------------------------------------------#
diff --git a/library/array.m b/library/array.m
index 2c08e3689..8b1988d3a 100644
--- a/library/array.m
+++ b/library/array.m
@@ -555,18 +555,18 @@ MR_MODULE_STATIC_OR_EXTERN MR_ModuleFunc array_module_builtins;
 
 /* Ensure that the initialization code for the above module gets run. */
 /*
-INIT sys_init_array_module_builtins
+INIT mercury_sys_init_array_module_builtins
 */
 
 /* suppress gcc -Wmissing-decl warning */
-void sys_init_array_module_builtins_init(void);
-void sys_init_array_module_builtins_init_type_tables(void);
+void mercury_sys_init_array_module_builtins_init(void);
+void mercury_sys_init_array_module_builtins_init_type_tables(void);
 #ifdef	MR_DEEP_PROFILING
-void sys_init_array_module_builtins_write_out_proc_statics(FILE *fp);
+void mercury_sys_init_array_module_builtins_write_out_proc_statics(FILE *fp);
 #endif
 
 void
-sys_init_array_module_builtins_init(void)
+mercury_sys_init_array_module_builtins_init(void)
 {
 #ifndef MR_HIGHLEVEL_CODE
 	array_module_builtins();
@@ -577,7 +577,7 @@ sys_init_array_module_builtins_init(void)
 }
 
 void
-sys_init_array_module_builtins_init_type_tables(void)
+mercury_sys_init_array_module_builtins_init_type_tables(void)
 {
 #ifndef MR_HIGHLEVEL_CODE
 	MR_register_type_ctor_info(
@@ -587,7 +587,7 @@ sys_init_array_module_builtins_init_type_tables(void)
 
 #ifdef	MR_DEEP_PROFILING
 void
-sys_init_array_module_builtins_write_out_proc_statics(FILE *fp)
+mercury_sys_init_array_module_builtins_write_out_proc_statics(FILE *fp)
 {
 	MR_write_out_proc_static(fp, (MR_ProcStatic *)
 		&MR_proc_static_compiler_name(array, __Unify__, array, 1, 0));
diff --git a/library/builtin.m b/library/builtin.m
index 99a83da95..c55f73e49 100644
--- a/library/builtin.m
+++ b/library/builtin.m
@@ -790,7 +790,7 @@ mercury__builtin__copy_2_p_1(MR_Mercury_Type_Info type_info,
 }
 
 /* forward decl, to suppress gcc -Wmissing-decl warning */
-void sys_init_copy_module(void);
+void mercury_sys_init_copy_module(void);
 
 #else /* ! MR_HIGHLEVEL_CODE */
 
@@ -885,20 +885,20 @@ MR_END_MODULE
 /* Ensure that the initialization code for the above module gets run. */
 
 /*
-INIT sys_init_copy_module
+INIT mercury_sys_init_copy_module
 */
 
 /* suppress gcc -Wmissing-decl warnings */
-void sys_init_copy_module_init(void);
-void sys_init_copy_module_init_type_tables(void);
+void mercury_sys_init_copy_module_init(void);
+void mercury_sys_init_copy_module_init_type_tables(void);
 #ifdef MR_DEEP_PROFILING
-void sys_init_copy_module_write_out_proc_statics(FILE *fp);
+void mercury_sys_init_copy_module_write_out_proc_statics(FILE *fp);
 #endif
 
 MR_MODULE_STATIC_OR_EXTERN MR_ModuleFunc copy_module;
 
 void
-sys_init_copy_module_init(void)
+mercury_sys_init_copy_module_init(void)
 {
 #ifndef MR_HIGHLEVEL_CODE
 	copy_module();
@@ -906,13 +906,13 @@ sys_init_copy_module_init(void)
 }
 
 void
-sys_init_copy_module_init_type_tables(void)
+mercury_sys_init_copy_module_init_type_tables(void)
 {
 }
 
 #ifdef	MR_DEEP_PROFILING
 void
-sys_init_copy_module_write_out_proc_statics(FILE *fp)
+mercury_sys_init_copy_module_write_out_proc_statics(FILE *fp)
 {
 	MR_write_out_proc_static(fp, (MR_ProcStatic *)
 		&mercury_data__proc_static__mercury__copy_2_0);
diff --git a/library/io.m b/library/io.m
index e45815e6a..ca3ca8696 100644
--- a/library/io.m
+++ b/library/io.m
@@ -1604,7 +1604,7 @@ io__read_line_as_string(Stream, Result, IO0, IO) :-
 	if (read_buffer != initial_read_buffer) {
 		MR_free(read_buffer);
 	}
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 io__read_line_as_string_2(_, _, _) -->
@@ -1774,7 +1774,7 @@ io__input_stream_foldl2_io(Stream, Pred, T0, Res) -->
 	} else {
 		/* Not a file stream so do nothing */
 	}
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("MC++", io__clear_err(_Stream::in, IO0::di, IO::uo),
@@ -1783,7 +1783,7 @@ io__input_stream_foldl2_io(Stream, Pred, T0, Res) -->
 	// XXX no error flag to reset as in MC++ an error throws directly an
 	// exception (we should create an error indicator in MF_Mercury_file
 	// for compatibility)
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 io__clear_err(_) -->
@@ -1822,7 +1822,7 @@ io__check_err(Stream, Res) -->
 
 	ML_maybe_make_err_msg(RetVal != 0, ""read failed: "",
 		MR_PROC_LABEL, RetStr);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("MC++", ferror(_Stream::in, RetVal::out, _RetStr::out,
@@ -1831,7 +1831,7 @@ io__check_err(Stream, Res) -->
 "{
 	// XXX see clearerr
 	RetVal = 0;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 ferror(_, _, _) -->
@@ -1851,7 +1851,7 @@ ferror(_, _, _) -->
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "{
 	ML_maybe_make_err_msg(MR_TRUE, Msg0, MR_PROC_LABEL, Msg);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("MC++", 
@@ -1908,7 +1908,7 @@ make_err_msg(_, _) -->
 #else
 	Size = -1;
 #endif
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("MC++", io__stream_file_size(Stream::in, Size::out,
@@ -1922,7 +1922,7 @@ make_err_msg(_, _) -->
 	} else {
 	       Size = -1;
 	}
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 io__stream_file_size(_, _) -->
@@ -1964,7 +1964,7 @@ io__file_modification_time(File, Result) -->
 	Msg = MR_make_string_const(
 	""io__file_modification_time not available on this platform"");
 #endif
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 
 }").
 
@@ -2084,7 +2084,7 @@ io__buffer_to_string(_, _) :-
 
 	Buffer = (MR_Word) buffer;
 	Pos = Pos0 + items_read;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 
@@ -2972,7 +2972,7 @@ io__stream_name(Stream, Name) -->
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	StreamNames = ML_io_stream_names;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C", 
@@ -2980,7 +2980,7 @@ io__stream_name(Stream, Name) -->
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	ML_io_stream_names = StreamNames;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++", 
@@ -2988,7 +2988,7 @@ io__stream_name(Stream, Name) -->
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	StreamNames = ML_io_stream_names;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++", 
@@ -2996,7 +2996,7 @@ io__stream_name(Stream, Name) -->
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	ML_io_stream_names = StreamNames;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 io__get_stream_names(_) -->
@@ -3038,7 +3038,7 @@ io__insert_stream_name(Stream, Name) -->
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	Globals = ML_io_user_globals;
-	update_io(IOState0, IOState);
+	MR_update_io(IOState0, IOState);
 ").
 
 :- pragma foreign_proc("C", 
@@ -3047,7 +3047,7 @@ io__insert_stream_name(Stream, Name) -->
 "
 	/* XXX need to globalize the memory */
 	ML_io_user_globals = Globals;
-	update_io(IOState0, IOState);
+	MR_update_io(IOState0, IOState);
 ").
 
 :- pragma foreign_proc("MC++", 
@@ -3055,7 +3055,7 @@ io__insert_stream_name(Stream, Name) -->
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	Globals = ML_io_user_globals;
-	update_io(IOState0, IOState);
+	MR_update_io(IOState0, IOState);
 ").
 
 :- pragma foreign_proc("MC++", 
@@ -3063,7 +3063,7 @@ io__insert_stream_name(Stream, Name) -->
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	ML_io_user_globals = Globals;
-	update_io(IOState0, IOState);
+	MR_update_io(IOState0, IOState);
 ").
 
 io__set_globals(_) -->
@@ -3229,13 +3229,13 @@ io__finalize_state -->
 #endif
 	MR_add_root(&ML_io_stream_names, (MR_TypeInfo) StreamNamesType);
 	MR_add_root(&ML_io_user_globals, (MR_TypeInfo) UserGlobalsType);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++", 
 		io__gc_init(_StreamNamesType::in, _UserGlobalsType::in,
 		IO0::di, IO::uo), [will_not_call_mercury, promise_pure], "
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 	ascii_encoder =	new System::Text::ASCIIEncoding();
 ").
 
@@ -3356,9 +3356,10 @@ extern MercuryFile *mercury_current_text_output;
 extern MercuryFile *mercury_current_binary_input;
 extern MercuryFile *mercury_current_binary_output;
 
-#define initial_io_state()		0	/* some random number */
-#define update_io(r_src, r_dest)	((r_dest) = (r_src))
-#define final_io_state(r)		((void)0)
+#define MR_initial_io_state()		0	/* some random number */
+#define MR_final_io_state(r)		((void)0)
+
+#define MR_update_io(r_src, r_dest)	((r_dest) = (r_src))
 
 void 		mercury_init_io(void);
 MercuryFile*	mercury_open(const char *filename, const char *openmode);
@@ -3402,9 +3403,9 @@ typedef __gc struct MR_MercuryFileStruct *MR_MercuryFile;
 #define ML_DownCast(Cast, Expr) dynamic_cast<Cast>(Expr)
 #define ML_UpCast(Cast, Expr) ((Cast) (Expr))
 
-#define initial_io_state()	0	/* some random number */
-#define update_io(r_src, r_dest)	(0)
-#define final_io_state(r)
+#define MR_initial_io_state()	0	/* some random number */
+#define MR_update_io(r_src, r_dest)	(0)
+#define MR_final_io_state(r)
 
 
 ").
@@ -3933,7 +3934,7 @@ ML_fprintf(MercuryFile* mf, const char *format, ...)
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	CharCode = mercury_getc((MercuryFile *) File);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C", 
@@ -3948,7 +3949,7 @@ ML_fprintf(MercuryFile* mf, const char *format, ...)
 	if (MR_UNGETCH(*mf, Character) == EOF) {
 		mercury_io_error(mf, ""io__putback_char: ungetc failed"");
 	}
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("C",
@@ -3960,7 +3961,7 @@ ML_fprintf(MercuryFile* mf, const char *format, ...)
 	if (MR_UNGETCH(*mf, Character) == EOF) {
 		mercury_io_error(mf, ""io__putback_byte: ungetc failed"");
 	}
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("MC++", 
@@ -3969,7 +3970,7 @@ ML_fprintf(MercuryFile* mf, const char *format, ...)
 	MR_MercuryFile mf = ML_DownCast(MR_MercuryFile, 
 		MR_word_to_c_pointer(File));
 	CharCode = mercury_getc(mf);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++", 
@@ -3982,7 +3983,7 @@ ML_fprintf(MercuryFile* mf, const char *format, ...)
 		mf->line_number--;
 	}
 	mf->stream->Seek(-1, System::IO::SeekOrigin::Current);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("MC++",
@@ -3992,7 +3993,7 @@ ML_fprintf(MercuryFile* mf, const char *format, ...)
 	MR_MercuryFile mf = ML_DownCast(MR_MercuryFile, 
 		MR_word_to_c_pointer(File));
 	mf->stream->Seek(-1, System::IO::SeekOrigin::Current);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 io__read_char_code(_, _) -->
@@ -4017,7 +4018,7 @@ io__putback_byte(_, _) -->
 		[may_call_mercury, promise_pure, tabled_for_io, thread_safe],
 "
 	mercury_print_string(mercury_current_text_output, Message);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C", 
@@ -4030,7 +4031,7 @@ io__putback_byte(_, _) -->
 	if (Character == '\\n') {
 		MR_line_number(*mercury_current_text_output)++;
 	}
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C",
@@ -4040,7 +4041,7 @@ io__putback_byte(_, _) -->
 	if (ML_fprintf(mercury_current_text_output, ""%ld"", (long) Val) < 0) {
 		mercury_output_error(mercury_current_text_output);
 	}
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C",
@@ -4050,7 +4051,7 @@ io__putback_byte(_, _) -->
 	if (ML_fprintf(mercury_current_text_output, ""%#.15g"", Val) < 0) {
 		mercury_output_error(mercury_current_text_output);
 	}
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C",
@@ -4063,7 +4064,7 @@ io__putback_byte(_, _) -->
 	{
 		mercury_output_error(mercury_current_text_output);
 	}
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C",
@@ -4071,7 +4072,7 @@ io__putback_byte(_, _) -->
 		[may_call_mercury, promise_pure, tabled_for_io, thread_safe],
 "{
 	mercury_print_binary_string(mercury_current_binary_output, Message);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("C", 
@@ -4081,7 +4082,7 @@ io__putback_byte(_, _) -->
 	if (MR_FLUSH(*mercury_current_text_output) < 0) {
 		mercury_output_error(mercury_current_text_output);
 	}
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C",
@@ -4091,7 +4092,7 @@ io__putback_byte(_, _) -->
 	if (MR_FLUSH(*mercury_current_binary_output) < 0) {
 		mercury_output_error(mercury_current_binary_output);
 	}
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++", 
@@ -4099,7 +4100,7 @@ io__putback_byte(_, _) -->
 		[may_call_mercury, promise_pure, thread_safe, tabled_for_io],
 "
 	mercury_print_string(mercury_current_text_output, Message);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++", 
@@ -4113,7 +4114,7 @@ io__putback_byte(_, _) -->
 	if (Character == '\\n') {
 		mercury_current_text_output->line_number++;
 	}
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++",
@@ -4121,7 +4122,7 @@ io__putback_byte(_, _) -->
 		[may_call_mercury, promise_pure, thread_safe, tabled_for_io],
 "
 	mercury_print_string(mercury_current_text_output, Val.ToString());
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++",
@@ -4129,7 +4130,7 @@ io__putback_byte(_, _) -->
 		[may_call_mercury, promise_pure, thread_safe, tabled_for_io],
 "
 	mercury_print_string(mercury_current_text_output, Val.ToString());
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++",
@@ -4149,7 +4150,7 @@ io__putback_byte(_, _) -->
 		[may_call_mercury, promise_pure, thread_safe, tabled_for_io],
 "{
 	mercury_print_binary_string(mercury_current_binary_output, Message);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("MC++", 
@@ -4157,7 +4158,7 @@ io__putback_byte(_, _) -->
 		[may_call_mercury, promise_pure, thread_safe, tabled_for_io],
 "
 	mercury_current_text_output->stream->Flush();
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++",
@@ -4165,7 +4166,7 @@ io__putback_byte(_, _) -->
 		[may_call_mercury, promise_pure, thread_safe, tabled_for_io],
 "
 	mercury_current_binary_output->stream->Flush();
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 io__write_string(_) -->
@@ -4239,7 +4240,7 @@ io__seek_binary(Stream, Whence, Offset, IO0, IO) :-
 		mercury_io_error(stream,
 				""io__seek_binary_2: unseekable stream"");
 	}
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("C",
@@ -4257,7 +4258,7 @@ io__seek_binary(Stream, Whence, Offset, IO0, IO) :-
 		mercury_io_error(stream,
 			""io__binary_stream_offset: untellable stream"");
 	}
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 io__seek_binary_2(_, _, _) -->
@@ -4278,7 +4279,7 @@ io__binary_stream_offset(_, _) -->
 "{
 	MercuryFile *stream = (MercuryFile *) Stream;
 	mercury_print_string(stream, Message);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("C",
@@ -4292,7 +4293,7 @@ io__binary_stream_offset(_, _) -->
 	if (Character == '\\n') {
 		MR_line_number(*stream)++;
 	}
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("C",
@@ -4303,7 +4304,7 @@ io__binary_stream_offset(_, _) -->
 	if (ML_fprintf(stream, ""%ld"", (long) Val) < 0) {
 		mercury_output_error(stream);
 	}
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("C",
@@ -4314,7 +4315,7 @@ io__binary_stream_offset(_, _) -->
 	if (ML_fprintf(stream, ""%#.15g"", Val) < 0) {
 		mercury_output_error(stream);
 	}
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("C",
@@ -4326,7 +4327,7 @@ io__binary_stream_offset(_, _) -->
 	if (MR_PUTCH(*stream, (int) ((unsigned char) Byte)) < 0) {
 		mercury_output_error(stream);
 	}
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("C",
@@ -4335,7 +4336,7 @@ io__binary_stream_offset(_, _) -->
 "{
 	MercuryFile *stream = (MercuryFile *) Stream;
 	mercury_print_binary_string(stream, Message);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("C",
@@ -4346,7 +4347,7 @@ io__binary_stream_offset(_, _) -->
 	if (MR_FLUSH(*stream) < 0) {
 		mercury_output_error(stream);
 	}
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("C",
@@ -4357,7 +4358,7 @@ io__binary_stream_offset(_, _) -->
 	if (MR_FLUSH(*stream) < 0) {
 		mercury_output_error(stream);
 	}
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("MC++",
@@ -4367,7 +4368,7 @@ io__binary_stream_offset(_, _) -->
 	MR_MercuryFile stream = ML_DownCast(MR_MercuryFile, 
 		MR_word_to_c_pointer(Stream));
 	mercury_print_string(stream, Message);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("MC++",
@@ -4380,7 +4381,7 @@ io__binary_stream_offset(_, _) -->
 		mercury_current_binary_output->stream);
 	w->Write(Character);
 	w->Flush();
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("MC++",
@@ -4393,7 +4394,7 @@ io__binary_stream_offset(_, _) -->
 		mercury_current_binary_output->stream);
 	w->Write(Val.ToString());
 	w->Flush();
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("MC++",
@@ -4406,7 +4407,7 @@ io__binary_stream_offset(_, _) -->
 		mercury_current_binary_output->stream);
 	w->Write(Val.ToString());
 	w->Flush();
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("MC++",
@@ -4421,7 +4422,7 @@ io__binary_stream_offset(_, _) -->
 		mercury_current_binary_output->stream);
 	w->Write(Byte.ToString());
 	w->Flush();
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("MC++",
@@ -4431,7 +4432,7 @@ io__binary_stream_offset(_, _) -->
 	MR_MercuryFile stream = ML_DownCast(MR_MercuryFile, 
 		MR_word_to_c_pointer(Stream));
 	mercury_print_binary_string(stream, Message);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("MC++",
@@ -4441,7 +4442,7 @@ io__binary_stream_offset(_, _) -->
 	MR_MercuryFile stream = ML_DownCast(MR_MercuryFile, 
 		MR_word_to_c_pointer(Stream));
 	stream->stream->Flush();
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("MC++",
@@ -4451,7 +4452,7 @@ io__binary_stream_offset(_, _) -->
 	MR_MercuryFile stream = ML_DownCast(MR_MercuryFile, 
 		MR_word_to_c_pointer(Stream));
 	stream->stream->Flush();
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 io__write_string(_, _) -->
@@ -4506,7 +4507,7 @@ io__flush_binary_output(_) -->
 			thread_safe],
 "
 	Stream = (MR_Word) &mercury_stdin;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C",
@@ -4515,7 +4516,7 @@ io__flush_binary_output(_) -->
 			thread_safe],
 "
 	Stream = (MR_Word) &mercury_stdout;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C",
@@ -4524,7 +4525,7 @@ io__flush_binary_output(_) -->
 			thread_safe],
 "
 	Stream = (MR_Word) &mercury_stderr;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C",
@@ -4533,7 +4534,7 @@ io__flush_binary_output(_) -->
 			thread_safe],
 "
 	Stream = (MR_Word) &mercury_stdin_binary;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C",
@@ -4542,7 +4543,7 @@ io__flush_binary_output(_) -->
 			thread_safe],
 "
 	Stream = (MR_Word) &mercury_stdout_binary;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C",
@@ -4550,7 +4551,7 @@ io__flush_binary_output(_) -->
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	Stream = (MR_Word) mercury_current_text_input;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C",
@@ -4558,7 +4559,7 @@ io__flush_binary_output(_) -->
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	Stream = (MR_Word) mercury_current_text_output;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C",
@@ -4566,7 +4567,7 @@ io__flush_binary_output(_) -->
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	Stream = (MR_Word) mercury_current_binary_input;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C",
@@ -4574,7 +4575,7 @@ io__flush_binary_output(_) -->
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	Stream = (MR_Word) mercury_current_binary_output;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C",
@@ -4582,7 +4583,7 @@ io__flush_binary_output(_) -->
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	LineNum = MR_line_number(*mercury_current_text_input);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C",
@@ -4591,7 +4592,7 @@ io__flush_binary_output(_) -->
 "{
 	MercuryFile *stream = (MercuryFile *) Stream;
 	LineNum = MR_line_number(*stream);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("C",
@@ -4599,7 +4600,7 @@ io__flush_binary_output(_) -->
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	MR_line_number(*mercury_current_text_input) = LineNum;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C",
@@ -4608,7 +4609,7 @@ io__flush_binary_output(_) -->
 "{
 	MercuryFile *stream = (MercuryFile *) Stream;
 	MR_line_number(*stream) = LineNum;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("C",
@@ -4616,7 +4617,7 @@ io__flush_binary_output(_) -->
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	LineNum = MR_line_number(*mercury_current_text_output);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 	
 :- pragma foreign_proc("C",
@@ -4625,7 +4626,7 @@ io__flush_binary_output(_) -->
 "{
 	MercuryFile *stream = (MercuryFile *) Stream;
 	LineNum = MR_line_number(*stream);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("C",
@@ -4633,7 +4634,7 @@ io__flush_binary_output(_) -->
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	MR_line_number(*mercury_current_text_output) = LineNum;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C",
@@ -4643,7 +4644,7 @@ io__flush_binary_output(_) -->
 "{
 	MercuryFile *stream = (MercuryFile *) Stream;
 	MR_line_number(*stream) = LineNum;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("C",
@@ -4651,7 +4652,7 @@ io__flush_binary_output(_) -->
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	OutStream = (MR_Word) mercury_current_text_input;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C",
@@ -4659,7 +4660,7 @@ io__flush_binary_output(_) -->
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	OutStream = (MR_Word) mercury_current_text_output;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C",
@@ -4667,7 +4668,7 @@ io__flush_binary_output(_) -->
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	OutStream = (MR_Word) mercury_current_binary_input;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C",
@@ -4675,7 +4676,7 @@ io__flush_binary_output(_) -->
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	OutStream = (MR_Word) mercury_current_binary_output;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 % io__set_input_stream(NewStream, OldStream, IO0, IO1)
@@ -4688,7 +4689,7 @@ io__flush_binary_output(_) -->
 "
 	OutStream = (MR_Word) mercury_current_text_input;
 	mercury_current_text_input = (MercuryFile *) NewStream;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C",
@@ -4698,7 +4699,7 @@ io__flush_binary_output(_) -->
 "
 	OutStream = (MR_Word) mercury_current_text_output;
 	mercury_current_text_output = (MercuryFile *) NewStream;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C",
@@ -4708,7 +4709,7 @@ io__flush_binary_output(_) -->
 "
 	OutStream = (MR_Word) mercury_current_binary_input;
 	mercury_current_binary_input = (MercuryFile *) NewStream;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C",
@@ -4718,7 +4719,7 @@ io__flush_binary_output(_) -->
 "
 	OutStream = (MR_Word) mercury_current_binary_output;
 	mercury_current_binary_output = (MercuryFile *) NewStream;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++",
@@ -4727,7 +4728,7 @@ io__flush_binary_output(_) -->
 			tabled_for_io],
 "
 	MR_c_pointer_to_word(Stream, mercury_stdin);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++",
@@ -4736,7 +4737,7 @@ io__flush_binary_output(_) -->
 			tabled_for_io],
 "
 	MR_c_pointer_to_word(Stream, mercury_stdout);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++",
@@ -4745,7 +4746,7 @@ io__flush_binary_output(_) -->
 			tabled_for_io],
 "
 	MR_c_pointer_to_word(Stream, mercury_stderr);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++",
@@ -4754,7 +4755,7 @@ io__flush_binary_output(_) -->
 			tabled_for_io],
 "
 	MR_c_pointer_to_word(Stream, mercury_stdin_binary);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++",
@@ -4763,7 +4764,7 @@ io__flush_binary_output(_) -->
 			tabled_for_io],
 "
 	MR_c_pointer_to_word(Stream, mercury_stdout_binary);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++",
@@ -4771,7 +4772,7 @@ io__flush_binary_output(_) -->
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	MR_c_pointer_to_word(Stream, mercury_current_text_input);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++",
@@ -4779,7 +4780,7 @@ io__flush_binary_output(_) -->
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	MR_c_pointer_to_word(Stream, mercury_current_text_output);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++",
@@ -4787,7 +4788,7 @@ io__flush_binary_output(_) -->
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	MR_c_pointer_to_word(Stream, mercury_current_binary_input);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++",
@@ -4795,7 +4796,7 @@ io__flush_binary_output(_) -->
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	MR_c_pointer_to_word(Stream, mercury_current_binary_output);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++",
@@ -4803,7 +4804,7 @@ io__flush_binary_output(_) -->
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	LineNum = mercury_current_text_input->line_number;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++",
@@ -4813,7 +4814,7 @@ io__flush_binary_output(_) -->
 	MR_MercuryFile stream = ML_DownCast(MR_MercuryFile, 
 		MR_word_to_c_pointer(Stream));
 	LineNum = stream->line_number;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("MC++",
@@ -4821,7 +4822,7 @@ io__flush_binary_output(_) -->
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	mercury_current_text_input->line_number = LineNum;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++",
@@ -4831,14 +4832,14 @@ io__flush_binary_output(_) -->
 	MR_MercuryFile stream = ML_DownCast(MR_MercuryFile, 
 		MR_word_to_c_pointer(Stream));
 	stream->line_number = LineNum;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("MC++",
 	io__get_output_line_number(LineNum::out, IO0::di, IO::uo),
 		[will_not_call_mercury, promise_pure, tabled_for_io], "
 	LineNum = mercury_current_text_output->line_number;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++",
@@ -4847,14 +4848,14 @@ io__flush_binary_output(_) -->
 	MR_MercuryFile stream = ML_DownCast(MR_MercuryFile, 
 		MR_word_to_c_pointer(Stream));
 	LineNum = stream->line_number;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 :- pragma foreign_proc("MC++",
 	io__set_output_line_number(LineNum::in, IO0::di, IO::uo),
 		[will_not_call_mercury, promise_pure, tabled_for_io], "
 	mercury_current_text_output->line_number = LineNum;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++",
@@ -4863,7 +4864,7 @@ io__flush_binary_output(_) -->
 	MR_MercuryFile stream = ML_DownCast(MR_MercuryFile, 
 		MR_word_to_c_pointer(Stream));
 	stream->line_number = LineNum;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 % io__set_input_stream(NewStream, OldStream, IO0, IO1)
@@ -4875,7 +4876,7 @@ io__flush_binary_output(_) -->
 	MR_c_pointer_to_word(OutStream, mercury_current_text_input);
 	mercury_current_text_input = 
 		ML_DownCast(MR_MercuryFile, MR_word_to_c_pointer(NewStream));
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++",
@@ -4884,7 +4885,7 @@ io__flush_binary_output(_) -->
 	MR_c_pointer_to_word(OutStream, mercury_current_text_output);
 	mercury_current_text_output = 
 		ML_DownCast(MR_MercuryFile, MR_word_to_c_pointer(NewStream));
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++",
@@ -4894,7 +4895,7 @@ io__flush_binary_output(_) -->
 	MR_c_pointer_to_word(OutStream, mercury_current_binary_input);
 	mercury_current_binary_input = 
 		ML_DownCast(MR_MercuryFile, MR_word_to_c_pointer(NewStream));
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++",
@@ -4904,7 +4905,7 @@ io__flush_binary_output(_) -->
 	MR_c_pointer_to_word(OutStream, mercury_current_binary_output);
 	mercury_current_binary_output = 
 		ML_DownCast(MR_MercuryFile, MR_word_to_c_pointer(NewStream));
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 io__stdin_stream(_) -->
@@ -5045,7 +5046,7 @@ io__set_binary_output_stream(_, _) -->
 "
 	Stream = (MR_Word) mercury_open(FileName, Mode);
 	ResultCode = (Stream ? 0 : -1);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++",
@@ -5057,7 +5058,7 @@ io__set_binary_output_stream(_, _) -->
 	MR_MercuryFile mf = mercury_open(FileName, Mode);
 	MR_c_pointer_to_word(Stream, mf);
 	ResultCode = (mf ? 0 : -1);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 io__do_open(_, _, _, _) -->
@@ -5086,7 +5087,7 @@ io__close_binary_output(Stream) -->
 :- pragma foreign_proc("C", io__close_stream(Stream::in, IO0::di, IO::uo),
 		[may_call_mercury, promise_pure, tabled_for_io, thread_safe], "
 	mercury_close((MercuryFile *) Stream);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++", io__close_stream(Stream::in, IO0::di, IO::uo),
@@ -5094,7 +5095,7 @@ io__close_binary_output(Stream) -->
 	MR_MercuryFile mf = ML_DownCast(MR_MercuryFile, 
 		MR_word_to_c_pointer(Stream));
 	mercury_close(mf);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 io__close_stream(_) -->
@@ -5124,7 +5125,7 @@ io__close_stream(_) -->
 	} else {
 		PrognameOut = DefaultProgname;
 	}
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C",
@@ -5140,7 +5141,7 @@ io__close_stream(_) -->
 			MR_PROC_LABEL);
 	  }
 	}
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C",
@@ -5148,7 +5149,7 @@ io__close_stream(_) -->
 		[will_not_call_mercury, promise_pure, tabled_for_io], 
 "
 	ExitStatus = mercury_exit_status;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C",
@@ -5156,7 +5157,7 @@ io__close_stream(_) -->
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	mercury_exit_status = ExitStatus;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("C",
@@ -5178,7 +5179,7 @@ io__close_stream(_) -->
 	} else {
 		Msg = MR_make_string_const("""");	
 	}
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 
@@ -5252,7 +5253,7 @@ io__handle_system_command_exit_code(Status0::in) = (Status::out) :-
 	while (--i > 0) {
 		MR_list_cons(Args, arg_vector[i], Args);
 	}
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 #endif
 ").
 
@@ -5261,7 +5262,7 @@ io__handle_system_command_exit_code(Status0::in) = (Status::out) :-
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	ExitStatus = System::Environment::get_ExitCode();
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 :- pragma foreign_proc("MC++",
@@ -5269,7 +5270,7 @@ io__handle_system_command_exit_code(Status0::in) = (Status::out) :-
 		[will_not_call_mercury, promise_pure, tabled_for_io],
 "
 	System::Environment::set_ExitCode(ExitStatus);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 
 /* XXX Implementation needs to be finished.
@@ -5286,7 +5287,7 @@ io__handle_system_command_exit_code(Status0::in) = (Status::out) :-
 	mercury::runtime::Errors::SORRY(""foreign code for this function"");
 //	Diagnostics::Process::Start(commandstr, argstr);
 	Status = NULL;
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 ").
 */
 
@@ -5468,7 +5469,7 @@ io__make_temp(Dir, Prefix, Name) -->
 			MR_PROC_LABEL, ErrorMessage);
 		Error = err;
 	}
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 io__do_make_temp(_, _, _, _, _) -->
@@ -5542,7 +5543,7 @@ io__remove_file(FileName, Result, IO0, IO) :-
 	RetVal = remove(FileName);
 	ML_maybe_make_err_msg(RetVal != 0, ""remove failed: "",
 		MR_PROC_LABEL, RetStr);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 /* XXX Implementation needs to be finished.
@@ -5556,7 +5557,7 @@ io__remove_file(FileName, Result, IO0, IO) :-
 	System::IO::File::Delete(FileName);
 	RetVal = 0;
 	RetStr = """";
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 */
 
@@ -5585,7 +5586,7 @@ io__rename_file(OldFileName, NewFileName, Result, IO0, IO) :-
 	RetVal = rename(OldFileName, NewFileName);
 	ML_maybe_make_err_msg(RetVal != 0, ""rename failed: "",
 		MR_PROC_LABEL, RetStr);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 
 io__rename_file_2(_, _, _, _) -->
diff --git a/library/time.m b/library/time.m
index a58277ede..87464cd23 100644
--- a/library/time.m
+++ b/library/time.m
@@ -167,7 +167,7 @@
 		#include <sys/times.h>
 	#endif
 
-	#define update_io(r_src, r_dest)	((r_dest) = (r_src))
+	#define MR_update_io(r_src, r_dest)	((r_dest) = (r_src))
 
 	#include ""mercury_string.h"" /* for MR_make_aligned_string_copy() */
 ").
@@ -192,7 +192,7 @@ time__clock(Result, IO0, IO) :-
 	[will_not_call_mercury, promise_pure, tabled_for_io],
 "{
 	Ret = (MR_Integer) clock();
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 time__c_clock(_) -->
 	% This version is only used for back-ends for which there is no
@@ -253,7 +253,7 @@ time__times(Tms, Result, IO0, IO) :-
 #else
 	Ret = -1;
 #endif
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 time__c_times(_, _, _, _, _) -->
 	% This version is only used for back-ends for which there is no
@@ -282,7 +282,7 @@ time__time(Result, IO0, IO) :-
 	[will_not_call_mercury, promise_pure, tabled_for_io],
 "{
 	Ret = (MR_Integer) time(NULL);
-	update_io(IO0, IO);
+	MR_update_io(IO0, IO);
 }").
 time__c_time(_) -->
 	% This version is only used for back-ends for which there is no
diff --git a/runtime/Mmakefile b/runtime/Mmakefile
index 8ca509890..9b4fe64f8 100644
--- a/runtime/Mmakefile
+++ b/runtime/Mmakefile
@@ -4,25 +4,6 @@
 # Public License - see the file COPYING in the Mercury distribution.
 #-----------------------------------------------------------------------------#
 
-# Mmake - Mmake file for the Mercury runtime library
-
-MAIN_TARGET=runtime
-
-MERCURY_DIR=..
-LINK_BOEHM_GC_ONLY=yes
-include $(MERCURY_DIR)/Mmake.common
--include Mmake.runtime.params
-
-# Avoid trying to make this file with `mmc --make' if it doesn't exist.
-Mmake.runtime.params: ;
-
-#-----------------------------------------------------------------------------#
-
-CFLAGS	+= -g $(DLL_CFLAGS) -DMERCURY_BOOTSTRAP_H -DMERCURY_CONF_BOOTSTRAP_H
-MGNUCFLAGS	+= --no-ansi
-
-#-----------------------------------------------------------------------------#
-
 # All the headers in $(HDRS) should be syntactically well-formed
 # header files, unlike the headers in $(BODY_HDRS).
 # All the headers in $(HDRS) must also be in C (not C++).
@@ -187,6 +168,36 @@ CFILES		= 	\
 			mercury_type_tables.c	\
 			mercury_wrapper.c
 
+#-----------------------------------------------------------------------------#
+
+# Mmake - Mmake file for the Mercury runtime library
+
+MAIN_TARGET=runtime
+
+# Specify which files to check for namespace cleanliness, and which name
+# prefixes are allowed.
+
+CHECK_HDRS  = $(HDRS)
+CHECK_MHDRS =
+CHECK_OBJS  = $(CFILES:.c=.$O)
+ALLOW_LIB_PREFIX=no
+ALLOW_BROWSER_PREFIX=no
+
+MERCURY_DIR=..
+LINK_BOEHM_GC_ONLY=yes
+include $(MERCURY_DIR)/Mmake.common
+-include Mmake.runtime.params
+
+# Avoid trying to make this file with `mmc --make' if it doesn't exist.
+Mmake.runtime.params: ;
+
+#-----------------------------------------------------------------------------#
+
+CFLAGS	+= -g $(DLL_CFLAGS) -DMERCURY_BOOTSTRAP_H -DMERCURY_CONF_BOOTSTRAP_H
+MGNUCFLAGS	+= --no-ansi
+
+#-----------------------------------------------------------------------------#
+
 OBJS		= $(CFILES:.c=.$O)
 PIC_OBJS	= $(CFILES:.c=.$(EXT_FOR_PIC_OBJECTS))
 
@@ -199,11 +210,6 @@ THREADLIBS	= \
 		  esac							\
 		`
 
-HDR_CHECK_CS = $(HDRS:.h=.check_hdr.c)
-HDR_CHECK_OBJS = $(HDRS:.h=.check_hdr.$O)
-HDR_CHECK_MACROS = $(HDRS:.h=.check.macros)
-OBJ_CHECKS = $(OBJS:%=%.obj_check)
-
 $(HDR_CHECK_OBJS):	mercury_conf.h
 
 #-----------------------------------------------------------------------------#
@@ -315,42 +321,6 @@ cs: $(CFILES)
 tags: $(CFILES) $(HDRS) $(BODY_HDRS)
 	ctags $(CFILES) $(HDRS) $(BODY_HDRS)
 
-#-----------------------------------------------------------------------------#
-#
-# `mmake check_namespace' performs various checks on the header files
-# and object files to make sure that they conform with our coding standards.
-#
-
-# Macro names must normally start with one of the prefixes associated
-# with the different components of our system:
-# 	`MR_' or `MERCURY_' for stuff in the Mercury runtime implementation
-# 		(the `runtime' and `trace' directories)
-# 	`GC_' for stuff in the Boehm et al conservative garbage collector
-# 		(the `boehm_gc' directory)
-# 	`MPS_' or `mps_' for stuff in the Memory Pool System toolkit
-# 		(the `mps_gc' directory, if present -- note that this
-# 		is in a separate CVS module and is not included in the
-# 		normal Mercury source distributions)
-# Exceptions to this policy must be listed in the RESERVED_MACRO_NAMES file.
-HEADER_CLEAN_FILTER = \
-	grep -v -e '^MR_' -e '^MERCURY_' -e '^GC_' -e '^MPS_' -e '^mps_' | \
-	fgrep -v -x -f RESERVED_MACRO_NAMES
-
-.PHONY: check_headers_self_contained
-check_headers_self_contained: $(HDR_CHECK_OBJS)
-
-.PHONY: check_headers_macros
-check_headers_macros: $(HDR_CHECK_MACROS)
-
-.PHONY: check_headers
-check_headers: check_headers_self_contained check_headers_macros
-
-.PHONY: check_objs
-check_objs: $(OBJ_CHECKS)
-
-.PHONY: check_namespace
-check_namespace: check_headers check_objs
-
 #-----------------------------------------------------------------------------#
 
 # installation rules
@@ -413,11 +383,6 @@ clean_local: clean_o clean_check
 clean_o:
 	rm -f $(OBJS) $(PIC_OBJS)
 
-.PHONY: clean_check
-clean_check:
-	rm -f $(HDR_CHECK_OBJS) $(HDR_CHECK_CS) $(HDR_CHECK_MACROS)
-	rm -f $(OBJ_CHECKS)
-
 .PHONY: realclean_local
 realclean_local:
 	rm -f lib$(RT_LIB_NAME).$A lib$(RT_LIB_NAME).so $(RT_LIB_NAME).init
diff --git a/runtime/RESERVED_MACRO_NAMES b/runtime/RESERVED_MACRO_NAMES
index 58b13ffdf..ca78bc13e 100644
--- a/runtime/RESERVED_MACRO_NAMES
+++ b/runtime/RESERVED_MACRO_NAMES
@@ -6,12 +6,10 @@
 #
 # RESERVED_MACRO_NAMES
 #
-# This file lists the macro names, other than the
-# ones starting with `MR_', `MERCURY_', or `GC_',
-# that are defined by the Mercury header files.
-# The Mmakefile target `check_headers' automatically
-# checks that no other macro names are defined.
-# This is done to keep our headers namespace-clean,
+# This file lists the macro names, other than the ones starting with a
+# certain set of allowed prefixes that are defined by the Mercury header files.
+# The Mmakefile target `check_headers' automatically checks that no other
+# macro names are defined. This is done to keep our headers namespace-clean,
 # i.e. ensure that we don't invade the user's namespace.
 #
 # This file is used as the argument to `fgrep -f'.
@@ -29,22 +27,6 @@ SUCCESS_INDICATOR
 # prefix this without requiring a later version of autoconf (e.g. 2.52).
 pid_t
 #-----------------------------------------------------------------------------#
-# These are defined by mercury.h
-# Normally macros should start with capital letters,
-# but in this case we need to use lowercase, otherwise
-# the macros wouldn't achieve their desired effect.
-# The `mercury__' prefix is unique enough.
-mercury__builtin____type_ctor_info_character_0
-mercury__builtin____type_ctor_info_float_0
-mercury__builtin____type_ctor_info_func_0
-mercury__builtin____type_ctor_info_int_0
-mercury__builtin____type_ctor_info_pred_0
-mercury__builtin____type_ctor_info_string_0
-mercury__builtin____type_ctor_info_tuple_0
-mercury__builtin____type_ctor_info_void_0
-mercury__private_builtin__SIZEOF_WORD
-mercury__private_builtin__unsafe_type_cast_2_p_0
-#-----------------------------------------------------------------------------#
 # These are defined by boehm_gc/gc.h.
 __GC
 _GC_H
diff --git a/tools/bootcheck b/tools/bootcheck
index 31dccf6f4..361ed585e 100755
--- a/tools/bootcheck
+++ b/tools/bootcheck
@@ -54,15 +54,14 @@ Options:
 		that is not compatible with the standard one.
 	-p, --copy-profiler
 		Copy the profiler directory instead of linking it.
-		This is sometimes necessary for bootstrapping
-		changes.
+		This is sometimes necessary for bootstrapping changes.
 	-b-, --no-bootcheck
 		Do not run the bootstrap check; execute the test suite and/or
 		the extras only. This option requires a previous bootstrap
 		check to have left a working stage 2 directory.
 	--no-check-namespace
-		Don't build the check_namespace targets in the runtime
-		and trace directories.
+		Don't build the check_namespace targets in the runtime,
+		trace, browser and library directories.
 	-t-, --no-test-suite
 		By default, bootcheck will also run the test quite.
 		This option prevents that.
@@ -247,6 +246,7 @@ while [ $# -gt 0 ]; do
 		runtests=false ;;
 
 	--skip-stage-2)
+		keep_stage_2=true
 		mmake_stage_2=false ;;
 
 	-2|--keep-stage-2)
@@ -661,20 +661,75 @@ then
 		fi
 	fi
 
+	# Build the check_namespace target in the relevant directories.
+	# We want to do so before we delete any of the stage2 object files.
+
+	check_namespace_status=0
+	if $check_namespace
+	then
+		cd $root/stage2/runtime
+		mmake $mmake_opts check_namespace || {
+			echo '** mmake check_namespace failed in runtime!'
+			check_namespace_status=1
+		}
+		cd $root/stage2/trace
+		mmake $mmake_opts check_namespace || {
+			echo '** mmake check_namespace failed in trace!'
+			check_namespace_status=1
+		}
+		cd $root/stage2/library
+		mmake $mmake_opts check_namespace || {
+			echo '** mmake check_namespace failed in library!'
+			check_namespace_status=1
+		}
+		cd $root/stage2/browser
+		mmake $mmake_opts check_namespace || {
+			echo '** mmake check_namespace failed in browser!'
+			check_namespace_status=1
+		}
+		cd $root
+	fi
+
 	if $stop_after_stage_2
 	then
 		echo "stopping after building stage 2"
 		exit 0
 	fi
 
-	# We can remove the library object files now,
-	# but we will keep the compiler objects for a while longer
+	# We can now remove the object files from most stage2 directories,
+	# but we will keep the compiler objects for a while longer.
 	if $keep_objs
 	then
 		true
 	else
-		find $root/stage2/library -name "*.o" -print |
-		xargs /bin/rm -f
+		libdirs="library browser"
+		if $copy_profiler
+		then
+			profdirs="profiler deep_profiler"
+		else
+			profdirs=
+		fi
+		if $copy_runtime
+		then
+			rundirs="runtime trace"
+		else
+			rundirs=
+		fi
+
+		objdirs="$libdirs $profdirs $rundirs"
+		for rmdir in $objdirs
+		do
+			cd $root/stage2/$rmdir
+			/bin/rm -f *.o *.pic_o
+		done
+
+		for cleandir in runtime trace library browser
+		do
+			cd $root/stage2/$cleandir
+			mmake clean_check
+		done
+
+		cd $root
 	fi
 
 	MERCURY_COMPILER=$root/stage2/compiler/mercury_compile
@@ -939,26 +994,6 @@ fi
 
 #-----------------------------------------------------------------------------#
 
-# build the check_namespace target in the runtime directory
-
-check_namespace_status=0
-if $check_namespace
-then
-	cd $root/${stage2_insert}runtime
-	mmake $mmake_opts check_namespace || {
-		echo '** mmake check_namespace failed!'
-		check_namespace_status=1
-	}
-	cd $root/${stage2_insert}trace
-	mmake $mmake_opts check_namespace || {
-		echo '** mmake check_namespace failed!'
-		check_namespace_status=1
-	}
-	cd $root
-fi
-
-#-----------------------------------------------------------------------------#
-
 # Run the tests in the tests/* directories
 
 test_status=0
diff --git a/trace/Mmakefile b/trace/Mmakefile
index e10dac500..200f1562e 100644
--- a/trace/Mmakefile
+++ b/trace/Mmakefile
@@ -7,29 +7,6 @@
 # Mmakefile for the Mercury trace library, which contains the runtime
 # system components that are needed only if some procedures are traced.
 
-MAIN_TARGET=trace
-
-MERCURY_DIR=..
-LINK_STDLIB_ONLY=yes
-include $(MERCURY_DIR)/Mmake.common
--include Mmake.trace.params
-
-# Avoid trying to make this file with `mmc --make' if it doesn't exist.
-Mmake.trace.params: ;
-
-#-----------------------------------------------------------------------------#
-
-CFLAGS		+= -I$(BROWSER_DIR) -g $(DLL_CFLAGS) \
-			-DMR_NO_BACKWARDS_COMPAT -DMERCURY_CONF_BOOTSTRAP_H
-MGNUCFLAGS	+= --no-ansi
-
-#-----------------------------------------------------------------------------#
-
-# mercury_readline.c #includes the GNU readline headers, which
-# lack prototypes and `const', so we need to disable warnings
-# when compiling that file.
-MGNUCFLAGS-mercury_trace_readline = --no-check
-
 #-----------------------------------------------------------------------------#
 
 # keep this list in alphabetical order, please
@@ -77,11 +54,6 @@ RUNTIME_HDRS	=	\
 OBJS		= $(CFILES:.c=.$O)
 PIC_OBJS	= $(CFILES:.c=.$(EXT_FOR_PIC_OBJECTS))
 
-HDR_CHECK_CS	= $(HDRS:.h=.check_hdr.c)
-HDR_CHECK_OBJS	= $(HDRS:.h=.check_hdr.$O)
-HDR_CHECK_MACROS = $(HDRS:.h=.check.macros)
-OBJ_CHECKS	= $(OBJS:%=%.obj_check)
-
 LDFLAGS		= -L$(BROWSER_DIR) -L$(LIBRARY_DIR) \
 			-L$(RUNTIME_DIR) -L$(BOEHM_GC_DIR) -L/usr/local/lib
 LDLIBS		= -l$(BROWSER_LIB_NAME) $(MLLIBS) $(SOCKET_LIBRARY) \
@@ -91,6 +63,37 @@ THREADLIBS	= \
 		    *.par*) echo "-lpthread" ;;				\
 		  esac							\
 		`
+MAIN_TARGET=trace
+
+# Specify which files to check for namespace cleanliness, and which name
+# prefixes are allowed.
+
+CHECK_HDRS  = $(HDRS)
+CHECK_MHDRS =
+CHECK_OBJS  = $(OBJS)
+ALLOW_LIB_PREFIX=no
+ALLOW_BROWSER_PREFIX=no
+
+MERCURY_DIR=..
+LINK_STDLIB_ONLY=yes
+include $(MERCURY_DIR)/Mmake.common
+-include Mmake.trace.params
+
+# Avoid trying to make this file with `mmc --make' if it doesn't exist.
+Mmake.trace.params: ;
+
+#-----------------------------------------------------------------------------#
+
+CFLAGS		+= -I$(BROWSER_DIR) -g $(DLL_CFLAGS) \
+			-DMR_NO_BACKWARDS_COMPAT -DMERCURY_CONF_BOOTSTRAP_H
+MGNUCFLAGS	+= --no-ansi
+
+#-----------------------------------------------------------------------------#
+
+# mercury_readline.c #includes the GNU readline headers, which
+# lack prototypes and `const', so we need to disable warnings
+# when compiling that file.
+MGNUCFLAGS-mercury_trace_readline = --no-check
 
 #-----------------------------------------------------------------------------#
 
@@ -147,33 +150,6 @@ cs: $(CFILES)
 tags: $(CFILES) $(HDRS)
 	ctags $(CFILES) $(HDRS) $(RUNTIME_DIR)/*.c $(RUNTIME_DIR)/*.h
 
-#-----------------------------------------------------------------------------#
-#
-# `mmake check_namespace' performs various checks on the header files
-# and object files to make sure that they conform with our coding standards.
-#
-
-# This should match the definition of HEADER_CLEAN_FILTER in
-# runtime/Mmakefile.  See the documentation there.
-HEADER_CLEAN_FILTER = \
-	grep -v -e '^MR_' -e '^MERCURY_' -e '^MPS_' -e '^mps_' -e '^GC_' | \
-	fgrep -v -x -f $(RUNTIME_DIR)/RESERVED_MACRO_NAMES
-
-.PHONY: check_headers_self_contained
-check_headers_self_contained: $(HDR_CHECK_OBJS)
-
-.PHONY: check_headers_macros
-check_headers_macros: $(HDR_CHECK_MACROS)
-
-.PHONY: check_headers
-check_headers: check_headers_self_contained check_headers_macros
-
-.PHONY: check_objs
-check_objs: $(OBJ_CHECKS)
-
-.PHONY: check_namespace
-check_namespace: check_headers check_objs
-
 #-----------------------------------------------------------------------------#
 
 # installation rules
@@ -214,11 +190,6 @@ clean_local: clean_o clean_check
 clean_o:
 	rm -f $(OBJS) $(PIC_OBJS)
 
-.PHONY: clean_check
-clean_check:
-	rm -f $(HDR_CHECK_OBJS) $(HDR_CHECK_CS) $(HDR_CHECK_MACROS)
-	rm -f $(OBJ_CHECKS)
-
 .PHONY: realclean_local
 realclean_local:
 	rm -f lib$(TRACE_LIB_NAME).$A lib$(TRACE_LIB_NAME).so