[dalke]

The commentary is a subset of what's in the wonderful M-W "Concise Dictionary of English Usage." The entry for "data, datum" starts "The word data is a queer fish."

The most complete online version of it that Google knows about is at http://www-old.accademiadellacrusca.it/forum/htdocs/phpBB2/v... .

Some key points and quotes:

- data isn't an ordinary plural. "Ordinary plurals ... can be modified by cardinal numbers; ... no one, it seems, can tell you how many data."

- "To summarize, data has never been the plural of a count noun in English. It is used in two constructions - plural, with plural apparatus, and singular, as a mass noun, with singular apparatus. Both constructions are fully standard at any level of formality. The plural construction is more common. If you are an editor for a publisher whose house style insists on the plural construction only, take care to be consistent ..."

- "There have been more occurrences of datum in popular sources since [about the middle 1960s]. Perhaps the insistence of many editors that data is a plural has accelerated the tendency for datum to be used as a singular of data"