Abbreviations

I’m using a footnote-stye format, a heavily adapted MHRA style, and using Footnote references almost exclusively in the document, generating a separate bibliography. I have a problem, however, with abbreviations, as I can’t find any mechanism for to replace references in the abbreviation list with appropriate abbreviations. Is there such a mechanism? “Irfan Shahid, Byzantium and the Arabs in the Sixth Century Part II”, for example, needs to be just “BASIC2”, “Oxford Classical Dictionary 2nd edn.” should be “OCD2” with a 2 superscript. Thanks, John