diff --git a/Headers/Additions/GNUstepBase/GNUstep.h b/Headers/Additions/GNUstepBase/GNUstep.h
index 550a43e29..fa5a97cad 100644
--- a/Headers/Additions/GNUstepBase/GNUstep.h
+++ b/Headers/Additions/GNUstepBase/GNUstep.h
@@ -75,6 +75,139 @@ NSAutoreleasePool *(X) = [NSAutoreleasePool new]
#define NSLocalizedStaticString(X, Y) X
+
+/*
+ * Check consistency of definitions for system compatibility.
+ */
+#if defined(STRICT_OPENSTEP)
+#define GS_OPENSTEP_V 010000
+#define NO_GNUSTEP 1
+#elif defined(STRICT_MACOS_X)
+#define GS_OPENSTEP_V 100000
+#define NO_GNUSTEP 1
+#else
+#undef NO_GNUSTEP
+#endif
+
+/*
+ * NB. The version values below must be integers ... by convention these are
+ * made up of two digits each for major, minor and subminor version numbers
+ * (ie each is in the range 00 to 99 though a leading zero in the major
+ * number is not permitted).
+ * So for a MacOS-X 10.3.9 release the version number would be 100309
+ *
+ * You may define GS_GNUSTEP_V or GS_OPENSTEP_V to ensure that your
+ * program only 'sees' the specified varsion of the API.
+ */
+
+/**
+ * Macro to check a defined GNUstep version number (GS_GNUSTEP_V) against
+ * the supplied arguments. Returns true if no GNUstep version is specified,
+ * or if ADD <= version < REM, where ADD is the version
+ * number at which a feature guarded by the macro was introduced and
+ * REM is the version number at which it was removed.
+ *
+ * The version number arguments are six digit integers where the first
+ * two digits are the major version number, the second two are the minor
+ * version number and the last two are the subminor number (all left padded
+ * with a zero where necessary). However, for convenience you can also
+ * use any of several predefined constants ...
+ * [GS_API_NONE],
+ * [GS_API_LATEST],
+ * [GS_API_OSSPEC],
+ * [GS_API_OPENSTEP],
+ * [GS_API_MACOSX]
+ *
+ * Also see [OS_API_VERSION]
+ *
+ * NB. If you are changing the API (eg adding a new feature) you need
+ * to control the visibility io the new header file code using
+ * #if GS_API_VERSION(ADD,GS_API_LATEST)
+ * where ADD is the version number of the next minor
+ * release after the most recent one.
+ * As a general principle you should not change the API with
+ * changing subminor version numbers ... as that tends to confuse
+ * people (though Apple has sometimes done it).
+ *
+ */
+#define GS_API_VERSION(ADD,REM) \
+ (!defined(GS_GNUSTEP_V) || (GS_GNUSTEP_V >= ADD && GS_GNUSTEP_V < REM))
+
+/**
+ * Macro to check a defined OpenStep/OPENSTEP/MacOS-X version against the
+ * supplied arguments. Returns true if no version is specified, or if
+ * ADD <= version < REM, where ADD is the version
+ * number at which a feature guarded by the macro was introduced and
+ * REM is the version number at which it was removed.
+ *
+ * The version number arguments are six digit integers where the first
+ * two digits are the major version number, the second two are the minor
+ * version number and the last two are the subminor number (all left padded
+ * with a zero where necessary). However, for convenience you can also
+ * use any of several predefined constants ...
+ * [GS_API_NONE],
+ * [GS_API_LATEST],
+ * [GS_API_OSSPEC],
+ * [GS_API_OPENSTEP],
+ * [GS_API_MACOSX]
+ *
+ * Also see [GS_API_VERSION]
+ *
+ */
+#define OS_API_VERSION(ADD,REM) \
+ (!defined(GS_OPENSTEP_V) || (GS_OPENSTEP_V >= ADD && GS_OPENSTEP_V < REM))
+
+/**
+ * A constant which is the lowest possible version number (0) so that
+ * when used as the removal version (second argument of the GS_API_VERSION
+ * or OS_API_VERSION macro) represents a feature which is not present in
+ * any version.
+ * eg.
+ * #if [OS_API_VERSION]
+ * (GS_API_NONE, GS_API_NONE)
+ * denotes code not present in OpenStep/OPENSTEP/MacOS-X
+ */
+#define GS_API_NONE 0
+
+/**
+ * A constant to represent a feature which is still present in the latest
+ * version. This is the highest possible version number.
+ * eg.
+ * #if [OS_API_VERSION]
+ * (GS_API_MACOSX, GS_API_LATEST)
+ * denotes code present from the initial MacOS-X version onwards.
+ */
+#define GS_API_LATEST 999999
+
+/**
+ * The version number of the initial OpenStep specification.
+ * eg.
+ * #if [OS_API_VERSION]
+ * (GS_API_OSSPEC, GS_API_LATEST)
+ * denotes code present from the OpenStep specification onwards.
+ */
+#define GS_API_OSSPEC 10000
+
+/**
+ * The version number of the first OPENSTEP implementation.
+ * eg.
+ * #if [OS_API_VERSION]
+ * (GS_API_OPENSTEP, GS_API_LATEST)
+ * denotes code present from the initial OPENSTEP version onwards.
+ */
+#define GS_API_OPENSTEP 40000
+
+/**
+ * The version number of the first MacOS-X implementation.
+ * eg.
+ * #if [OS_API_VERSION]
+ * (GS_API_MACOSX, GS_API_LATEST)
+ * denotes code present from the initial MacOS-X version onwards.
+ */
+#define GS_API_MACOSX 100000
+
+#else
+#include
#endif /* GNUSTEP */
#endif /* __GNUSTEP_GNUSTEP_H_INCLUDED_ */
diff --git a/Headers/Additions/GNUstepBase/GSFunctions.h b/Headers/Additions/GNUstepBase/GSFunctions.h
index 8940e6b90..d17b921e6 100644
--- a/Headers/Additions/GNUstepBase/GSFunctions.h
+++ b/Headers/Additions/GNUstepBase/GSFunctions.h
@@ -37,9 +37,9 @@
extern "C" {
#endif
+#if GS_API_VERSION(GS_API_NONE,011500)
@class NSArray;
@class NSString;
-#if GS_API_VERSION(GS_API_NONE,011500)
/**
* Try to locate file/directory (aName).(anExtension) in paths.
* Will return the first found or nil if nothing is found.