I have tried exporting the text contents of aTextFrame using the Export to RTF option..
Although MS-Word and MS-WordPad successfully read the file so produced, every 3rd party library I tried to convert RTF to HTML (both open source and propietary) failed to read the file. The 3rd party products either return an empty HTML or complain about duplicate font defintions.
Interestingly, if I take the RTF produced byInDesign and save it in MS-Word, the saved file can then be read succesfully by all other 3rd party libraries.
Any ideas? The file produced by MS-Word after the re-save is so radically different from the RTF originally produced by InDesign that there's no point attempting to compare the files visually.