Since at is not a word here, but just two subfields a and t, they should not have been translated of course. Incidentally, bij is the Dutch translation of the English at. The word gets translated and so subfields a and t are replaced by b, i and j. In most cases resulting in no information.
That's why the context (the comment for translator) is so important. A translator, knowing that 'at' comes from a .xsl file should suspect that it isn't a isolate word but a parameter, and taking a look at the XSL file he could see that the text comes from a XSLT template parameter. I agree that at the first place, there is something wrong in our XSL file strings extractor. There are also shortcomings in the other file types strings extractors. The .po files are huge for some of those reasons. We can discuss how to improve Koha localization/translation process. The goal could be to: simplify translators work, improve string extraction, improve Koha 'localizability', reduce .po files size. For XSL files, we could (1) explicitly mark text to be translated or (2) pick them up from an external XML file (performance warning). Regards, -- Frédéric DEMIANS http://www.tamil.fr/u/fdemians.html