This is available for a particular corner case due to our use of full-
word format specifiers.
Case: "%couch" is that %c followed by ouch, or is that the handled
format specifier '%couch' ?
If '%couch' is not registered there is no fallback to finding '%c'
(maybe one day), so in this case one must write "%c$ouch" and '%c'
becomes the specifier and the output for 'p' will be "pouch" and for
"%c$$ouch" the output will be "p$ouch."
