This is a somewhat more debated topic than the short commit message, so I thought I'd drop a couple of URLs in here for other perspectives, in case anyone is curious. (I don't care one way or the other how it's used in the tz archive, and am happy for Paul to follow his own personal preference, but I find the general topic interesting.) The question is whether data is still treated as the plural of datum, or whether it's converted into being a mass noun in its own right. It clearly started as the plural form of a count noun originally, but it's increasingly being used as a mass noun. My personal sense is that the movement towards data as a mass noun is substantial and has a great deal of momentum, and that in a few more decades it will be entrenched as a mass noun. http://www.motherjones.com/kevin-drum/2012/07/more-data-please http://www.quickanddirtytips.com/education/grammar/is-data-singular-or-plura... Re-running the ngram in the first URL shows a very similar graph as two years ago: https://books.google.com/ngrams/graph?content=data+is%2Cdata+are&year_start=... -- Russ Allbery (eagle@eyrie.org) <http://www.eyrie.org/~eagle/>