Transformations on "Formatted Strings"
for example "[DIRKEY /NoSlash]" might mean remove the trailing slash,
"[DIRKEY /83]" would give you an 83 name, ""[DIRKEY /upper]",
"[DIRKEY /substring 2,3" etc.
This would remove the need for a lot of custom actions (and make MSIs more antispyware friendly).
Perhaps some of the syntax could be based on Windows "environment"
manipulations for substrings, left/right etc.