I have a suggestion for an additional non-standard option letter/modifier. Sometimes I have a filter that needs to run multiple times. Typically I will just make X duplicate lines in my filter file and that makes it run X times. Instead, it would be nice if there were an option to specify that a specific filter should be rerun repeatedly until it no longer matches the source (up to a certain number of iterations of course, to prevent infinite loops). It's not a very common need but in some cases it's impossible to re-format things the way I need with a single regex replacement. I've got maybe 5 filters that require it. One of them needs to be repeated up to 100 times, so my filter file has 100 identical lines with the same regex string.
Will this be possible in future versions?
Currently nobody is working on this and it's not on our TODO list:
http://ijbswa.cvs.sourceforge.net/viewvc/ijbswa/current/TODO?view=markup
External filters already "support" loops of course:
http://www.privoxy.org/user-manual/actions-file.html#EXTERNAL-FILTER
Supported using external filters.