>The class does not write binaries -- it directly writes the xml format files that comprise the xlsx file format. This is not a 'hack' -- it is a direct write. This is a new project on VFPx that I wrote and only released very recently.
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>It writes the XML files to the format specifications contained in EMA-376, 4th edition published December 2012 (Office Open XML File Formats).

Aha, so it's not the thing I saw (on the wiki perhaps, or here) which had long blocks of binaries for the 97/2003 format plus some. Well, see my reply to Antonio - in my experience Microsoft will only grudgingly accept any standardization of its file formats, and then will aban... sorry, will extend these standards in the next version. Perhaps they're changing in that respect. Either way, good luck with this - I wouldn't have the patience to write all that :).