zwgetf­date – Get pack­age or file date

The pack­age can fetch the date dec­la­ra­tion of pack­ages and files used by a doc­u­ment, and then pro­vide the in­for­ma­tion in macros. The fa­cil­i­ties pro­vide a means of ob­tain­ing the date of a pack­age be­ing doc­u­mented; this is mainly of use when doc/doc­strip.