"So lets define an unclean file first of all. In our world this would be a file that contained the source text and the target translation… so essentially what we call a bilingual file. In the olden days, not quite as old as my pictures, this would have been Bilingual DOC or TTX and today it’s more likely to be XLIFF. However, we still see questions being asked because a translator has been asked to provide the unclean file for their customer and they’re not sure how to do this. The task can become more confusing because technically an XLIFF is also an unclean file but this term generally refers to Bilingual DOC rather than XLIFF, and probably rather than TTX as well. This of course poses a problem if you have a modern translation environment because even if the tools you use are capable of creating an unclean file like this, the only real guarantee that the ..."
Via Stefano KaliFire