Change revision format

hi
I have been using a format for my revisions as shown below
In design = A-01 to A-99
Released = B to Z
but I now want to change this format to
In design = -01 to -99
Released = A to Z
I have been able to achieve the new format but when I check out adocument with the old revision format I am finding that when I tryand check the document in with the new revision format PDMworksdoes not recognise it and errors.
The only way I can find around this is to delete the originaldocument from the Vault and recheck it in with the new format. As Ihave 100's of documents with the old revision format I do not wantto do this, is their any other way I can check old documents inwith the new revision format???
Thanks DSolidworksWorkgroup Pdm