Auto Signatures like in this wiki are called "magic words" by mediawiki software designers  - that is, data  substituted at edit  time ({{{ ~~~~ }}} as signature, {{{ ~~~~~ }}} as date) or at  render time (so-called  //MAGICWORDS// ) are poorly provided in the syntax. 

Without complicating, may I suggest a structure in the creole schema to  handle "such arbitrary words as the wiki designer/creole user  might wish to  create"?

== Common Magic Words

* [[Signature]]
* [[DateTime]]
* Both in combination

== Suggestions
Syntax would be a single char prefix , hence <char><a-z><non-a-z terminator//

Problem: We use tilde as [[Escape Character Proposal|escape character]], so we need some other characters for this. 

== Syntax in other engines

The JSPWiki Creole filter implements one magic word, the autosignature, but only for conveniance reasons, not because of the spec. It was taken over from mediawiki markup.

MoinMoin uses @MAGICWORD@, for example @SIG@ for "-- UserName Date".