Usage:
/SUBSTITUTE text
When called from a trigger (directly or indirectly), the triggering text is replaced with text. After a /substitute, it will appear as if text came from the socket; the original text is lost. In particular, this means when /substitute is called from a fall-thru trigger, triggers of lower priority will be compared against text instead of the original text.
Example:
On a mud that uses MUFpage, you could set your #prepend string to "##page>", and define a trigger like:
/def -ah -t"##page> *" hilite_mufpage = /substitute %-1
This will match no matter what page format the sender uses, and strip off the "##page>" so you never see it.
See: triggers