- All names of variables and functions may be tested. Additionally, the following
- compile-features may be tested when prefixed with 'feature_': ncurses, slang,
- iconv, idn, dotlock, standalone, pop, nntp, imap, ssl, gnutls, sasl, sasl2,
- libesmtp, compressed, color, classic_pgp, classic_smime, gpgme, header_cache.
+ These commands allow testing for a variable, function or certain feature being
+ available or not respectively, before actually executing the command given.
+
+ ifdef (short for ``if defined'') only executes the command upon availability
+ while ifndef (short for ``if not defined'') does if not. The _\bc_\bo_\bm_\bm_\ba_\bn_\bd may be any
+ valid fraction of a configuration file.
+
+ All names of variables, functions and menus may be tested. Additionally, the
+ following compile-features may be tested when prefixed with 'feature_':
+ ncurses, slang, iconv, idn, dotlock, standalone, pop, nntp, imap, ssl, gnutls,
+ sasl, sasl2, libesmtp, compressed, color, classic_pgp, classic_smime, gpgme,
+ header_cache, gdbm, qdbm and db4.