The searching Syntax indicates the following capabilities:

• To search for content that contains "chalk" but NOT "cheese"
  chalk NOT cheese
  I found cases when this does not work and returns results that contains both words.
  It may be linked with fact that the first word mixes letters and digits: EN9100 NOT principles
  Same problem using the form:
  chalk -cheese

• To search for "butter" or "batter" you can use the search:
  b?tter
  I cannot get this to work and a search for "sim?lator" doesn't find my pages with "simulator"

• You can also use the wildcard in the middle of a term.
  b*tter doesn't work either.

We consider this as a serious problem because it is utmost important for the users to know that they can rely on the search engine. This is one of the key components in a Wiki system.