-.Sh 64-BIT COMPILATION
-When compiling for 64-bit architectures, the
-.Dv __LP64__
-macro will be defined to 1, and UNIX conformance is always on (the
-.Dv _DARWIN_FEATURE_UNIX_CONFORMANCE
-macro will also be defined to the SUS conformance level).
-Defining
-.Dv _NONSTD_SOURCE
-will cause a compilation error.
+.Pp
+In order to provide both legacy and conformance versions of functions, two
+versions of affected functions are provided. Legacy variants have symbol names
+with no suffix in order to maintain ABI compatibility. Conformance versions
+have a $UNIX2003 suffix appended to their symbol name. These $UNIX2003
+suffixes are automatically appended by the compiler tool-chain and should not
+be used directly.
+.Pp
+Platforms that were released after these updates only have conformance variants
+available and do not have a $UNIX2003 suffix.
+.Pp
+.TS
+center;
+c s s s s
+c c | c c c
+c c | c c c
+l c | c c c
+l c | c c c
+l c | c c c
+l c | c c c
+l c | c c c
+l c | c c c
+l c | c c c.
+T{
+.Dv i386
+T}
+=
+user defines deployment namespace conformance suffix
+ target
+_
+T{
+.Em (none)
+T} < 10.5 full 10.3 compatibility (none)
+T{
+.Em (none)
+T} >= 10.5 full SUSv3 conformance $UNIX2003
+T{
+.Em _NONSTD_SOURCE
+T} (any) full 10.3 compatibility (none)
+T{
+.Em _DARWIN_C_SOURCE
+T} < 10.4 full 10.3 compatibility (none)
+T{
+.Em _DARWIN_C_SOURCE
+T} >= 10.4 full SUSv3 conformance $UNIX2003
+T{
+.Em _POSIX_C_SOURCE
+T} < 10.4 strict 10.3 compatibility (none)
+T{
+.Em _POSIX_C_SOURCE
+T} >= 10.4 strict SUSv3 conformance $UNIX2003
+_
+.T&
+c s s s s
+c s s s s
+c c | c c c
+c c | c c c
+l c | c c c
+l c | c s s
+l c | c c c
+l c | c c c.
+T{
+.Dv Newer Architectures
+T}
+=
+user defines deployment namespace conformance suffix
+ target
+_
+T{
+.Em (none)
+T} (any) full SUSv3 conformance (none)
+T{
+.Em _NONSTD_SOURCE
+T} (any) (error)
+T{
+.Em _DARWIN_C_SOURCE
+T} (any) full SUSv3 conformance (none)
+T{
+.Em _POSIX_C_SOURCE
+T} (any) strict SUSv3 conformance (none)
+_
+.TE