Z:gnu-man-db-manpages--756cd7-The filters are deciphered by/en

The filters are deciphered by a number of means. Firstly, the command line option B<-p> or the environment variable $B is interrogated. If B<-p> was not used and the environment variable was not set, the initial line of the nroff file is parsed for a preprocessor string. To contain a valid preprocessor string, the first line must resemble