http://www.perlmonks.org?node_id=1053528


in reply to %% in perl mean

Binding Operators and Regexp Quote Like Operators

If the string in $var->{SPEC} contains the characters "%%", the first occurance of "%%" will be changed to whatever string is in the variable $var->{LEARN}{TEST}. (Assuming that if( QLearn('LEARN') ) is true.)