Rewrite literal character substitutions

Rewrite literal character substitutions, $$, $%, $@
The,  , and   characters are  normally metacharacters in rewrite rule templates. To insert a literal such character, quote it with a dollar character,. I.e.,  expands to a single  dollar sign,  ;    expands to a single percent,   (the percent is not interpreted as a  template field separator in this case); and   expands to a single at sign,    (also not interpreted as a field separator).

See also:
 * Rewrite rule template formats
 * Rewrite rule template substitutions and control sequences