Each edition of a Technical Document is known as a Revision.

A revision has two critical additional attributes, namely its date and revision reference.

It is common practice that revisions which are released later "supersede" previous revisions. However, it may not be necessary to issue a particular [sub] contractor or supplier with the latest edition if it does not affect the work being executed or supplies being provided.

If however a later revison is issued to a [sub] contractor or supplier, then that constitutes a variation to the Work Instruction.