http://l3tczdiiwoo63iwxty4lhs6p7eaxop5micbn7vbliydgv63x5zrrrfyd.onion/user-manual/filter-file.html
A content filter header line for a filter called "foo" could look like
this: FILTER: foo Replace all "foo" with "bar" Below that line, and up to the next header line, come the jobs that define what text replacements the filter
executes. They are specified in a syntax that imitates Perl 's s/// operator. If you are familiar with Perl, you will find this to be quite intuitive,
and may want to look at the PCRS documentation for the subtle...