compares two internet draft files and outputs the difference

 The purpose of this program is to compare two versions of an internet-draft,
 and as output produce a diff in one of several formats:
  * side-by-side html diff
  * paged wdiff output in a text terminal
  * a text file with changebars in the left margin
  * a simple unified diff output
 .
 It can also be used to compare ordinary (non-rfc) text files.
 .
 In all cases, internet-draft headers and footers are stripped before
 generating the diff, to produce a cleaner diff.