REL_ALLOC Compile in the relocatable memory allocator ralloc.c.
SYSTEM_MALLOC Use the system library's malloc.
subprocesses System can use subprocesses (for M-x shell for example). Defined by default, only MSDOS undefines it.
-USE_LISP_UNION_TYPE Define it in lisp.h to make Lisp_Object be a union type instead of the default int.
+DEBUG_LISP_OBJECT_TYPE Define it in lisp.h enable compile time checks on Lisp_Object use.
** System specific macros, described in detail in src/s/template.h
CLASH_DETECTION