It does not seem to be possible to directly convert sxm to txt, i.e. OpenOffice.org math files to text. However, it may be possible to simply copy and paste the data once they have been imported to a document, unless the math formula is really complex.
This conversion entry was verified by us and conversion from sxm to txt was flagged as wrong or not possible.
Usually this happens when the conversion would try to convert different types of data between each other, such as audio to image, or it is not possible because incompatibility between programs, caused by closed file formats, very limited support etc.
If you find entry that you feel is flagged as bad wrongly, please tell us in the discussion below with as much as information as possible so we can fix it.