1. In a peripheral unit for creating marked pages, said peripheral unit adapted to receive, interpret and respond to a plurality of control languages that may appear in an input data stream, a method for identifying occurrence of a language boundary between a first control language and a second control language, said language boundary indicating a cessation of commands configured in accord with said first control language and a commencement of commands configured in accord with said second control language, comprising the steps of: (a) determining if a command in said data stream requires a printing of an initial mark on a page and, if yes; (b) instituting a subroutine to further determine if a language boundary has been encountered; and (c) if yes, identifying a control language of the input data stream.