+@node Macro define and undefine
+@chapter Representation of #define and #undef
+
+This section describes the stabs support for macro define and undefine
+information, supported on some systems. (e.g., with @option{-g3}
+@option{-gstabs} when using GCC).
+
+A @code{#define @var{macro-name} @var{macro-body}} is represented with
+an @code{N_MAC_DEFINE} stab with a string field of
+@code{@var{macro-name} @var{macro-body}}.
+@findex N_MAC_DEFINE
+
+An @code{#undef @var{macro-name}} is represented with an
+@code{N_MAC_UNDEF} stabs with a string field of simply
+@code{@var{macro-name}}.
+@findex N_MAC_UNDEF
+
+For both @code{N_MAC_DEFINE} and @code{N_MAC_UNDEF}, the desc field is
+the line number within the file where the corresponding @code{#define}
+or @code{#undef} occurred.
+
+For example, the following C code:
+
+@example
+ #define NONE 42
+ #define TWO(a, b) (a + (a) + 2 * b)
+ #define ONE(c) (c + 19)
+
+ main(int argc, char *argv[])
+ @{
+ func(NONE, TWO(10, 11));
+ func(NONE, ONE(23));
+
+ #undef ONE
+ #define ONE(c) (c + 23)
+
+ func(NONE, ONE(-23));
+
+ return (0);
+ @}
+
+ int global;
+
+ func(int arg1, int arg2)
+ @{
+ global = arg1 + arg2;
+ @}
+@end example
+
+@noindent
+produces the following stabs (as well as many others):
+
+@example
+ .stabs "NONE 42",54,0,1,0
+ .stabs "TWO(a,b) (a + (a) + 2 * b)",54,0,2,0
+ .stabs "ONE(c) (c + 19)",54,0,3,0
+ .stabs "ONE",58,0,10,0
+ .stabs "ONE(c) (c + 23)",54,0,11,0
+@end example
+
+@noindent
+NOTE: In the above example, @code{54} is @code{N_MAC_DEFINE} and
+@code{58} is @code{N_MAC_UNDEF}.
+