Please remember that filters are not just plain strings. Your filters need to be written in lower-case, and certain characters and character combinations have special meanings. The most common are listed below:

Common built in special things!
%d - Matches any digit (0-9)
%D - Matches anything except digits
%a - Matches any letter (a-z)
%A - Matches anything except letters
%w - Matches any digit or letter
%W - Matches anything except digits or letters
%s - Matches any whitespace (space, tab, newline, etc).
%S - Matches anything except whitespace
%p - Matches any punctuation
%P - Matches anything except punctuation
. - Matches any character
^ - Matches the beginning of a line
$ - Matches the end of a line
[abc] - Matches any of the characters contained between the [] (in this case a, b, or c)
[^abc] - Matches any character *except those contained between the [] (in this case, anything *but* a, b, or c).


Repetition!
- - Matches the previous character 0 or more times until the first occurrance of the next character in the pattern.
* - Matches the previous character 0 or more times as many times as possible
+ - Matches the previous character 1 or more times
? - Matches the previous character 0 or 1 times

Escape!
Use the '%' symbol before any of the following characters to ignore their special meanings: ( ) . % + - * ? [ ^ $