Certainly in my last two posts I have had job specifications consisting of short clauses covering my responsibilities such as "Assist in maintaining and safeguarding the backup and recovery routines, testing and enhancing as appropriate"

in both cases the final clause is "Other duties commensurate with the grade and post as detailed by the Line Manager".

In my previous employment this was always item 10 in our job specs and whenever we had to do anything unusual we just said "Clause 10 again" - usually with a grin.