Further... In one specific instance, in the MIF, FrameMaker is claiming that the table heading style for the unstructured master page maps table is LetterGothicMT and missing, when it's absolutely LetterGothicLT and present. Telling it to forget the 'missing' font converts the table heading font to TimesNewRomanPSMT - but the font is still correct and LetterGothicLT in the document.
Inserting a new unstruct master page table does not reveal any missing fonts. This is all most confusing. Here's the MIF... <Tbl <TblID 14> <TblTag `UnstructMasterPageMaps'> <TblFormat <TblColumn <TblColumnNum 0> <TblColumnWidth 13.91412 pc> <TblColumnH <PgfTag `TableHeading'> <Pgf <PgfFont <FTag `'> <FPlatformName `M.TimesNewRomanPSMT.P'> <FFamily `Times New Roman'> <FVar `Regular'> <FWeight `Medium'> <FAngle `Regular'> <FPostScriptName `TimesNewRomanPSMT'> -- Steve