At this very moment we are discussing re-introducing the values on/off to the simple type ST_OnOff in the transitional part of OOXML.
Some countries (including Denmark and UK) argued during the DIS29500-process that the enumeration values "on" and "off" of the simple type ST_OnOff were inappropriate since they expanded the W3C Schema data type xsd:boolean. So at the BRM, these values were removed from the simply type ST_OnOff.
Now, that's all fine and dandy - only problem was that it made (according to a Microsoft estimate) 90% of all existing documents (and existing applications) non-conformant. Alex Brown demonstrated this in his article "OOXML and Office 2007 Conformanc: a smoke test". Further, it went directly aganst the scope of IS29500:2008 which was to "represent faithfully the existing corpus of word-processing documents, spreadsheets and presentations that have been produced by Microsoft Office pplications (from Microsoft Office 97 to Microsoft Office 2008, inclusive)".
So we have been disussing this quite a bit - because by re-introducing the values on/off would effectively be reversing a BRM decision ... in other words ... politically, it is a bit of a hot potatoe.
You might argue that this is a prime example of how Microsoft controls SC34/WG4 and how we simply align everything to what Microsoft or Microsoft Office does - but unless you consistantly opt for the sensational news, that position doesn't make very much sense.This has really nothing to do with aligning IS29500 with Microsoft Office; it has to do with aligning IS29500 with its scope.
Now, do note that we in WG4 cannot make decisions to alterating IS29500 - this is the prerogitive of the national bodies in SC34 or JTC1, so all we are doing is suggesting to the NBs that we think it is a good idea to reintroduce the two values.