Is it the intention that all prepositional phrases be so labelled – even the ones which seem to function perfectly well as adjectives or adverbs? Ƿidsiþ 06:26, 10 January 2010 (UTC)
The don't function perfectly well as adjectives and adverbs. They generally do not accept modification by "very" or "too" and do not readily appear after "become". I have yet to engage in a search for exceptions. I am not sure that a prepositional phrase that met those tests should be forced to join its cousins under the new banner. DCDuringTALK 12:12, 10 January 2010 (UTC)
Expanding a bit, consider "He is very in-the-know.", "He is very 'in the know'.", and *"He is very in the know." Though the last is probably attestable, the first two are more consistent with the distinctive vocal marking of the expression's unusual use as adjective. I would argue that the best presentation would have "in the know" as a PP and "in-the-know" as an adjective (adverb, too ???) (with RT links rather than alternative spellings, I think). IMHO, there is a rebuttable presumption that PP is the best presentation for the unhyphenated form and Adjective is best for the hyphenated form, especially in attributive use.
It would be useful to see some examples that didn't fit this pattern to test the proposal. Any nominations? DCDuringTALK 15:21, 30 January 2010 (UTC)