AP Style - one you safely should ignore

AP is out with some new style updates, and there's one you can safely ignore, if you choose to:

flood plain - two words

But that easily gets flooded out by "floodplain" as one word. While the Random House Dictionary at Dictionary.com shows it as two words, even the two other references cited there show it as one. Merriam-Webster shows it as one, American Heritage (through Yahoo) shows it as preferably one, and the New Oxford on my Mac also shows it as one.

Webster's New World 4, the dictionary tied to the AP Stylebook, shows it as two words, with the single word alternative, but I increasingly find WNW4 falling out of step with common usage and increasingly turn to American Heritage, which steers a more moderate path between the conservative WNW4 and the liberal M-W. (For example, look up gauntlet and gantlet in the "big three." AHD is probably right in its reasoning that usage has shifted to gauntlet, as in run the gauntlet, even though I grimace.)

Most federal and state agencies I can find use it as one word.

And, while not definitive, a Google search for the two-word version, returns 2 million (with some overlap from reference works showing "floodplain" as first choice but the two words as second), while the one word version returns 20 million.

This is one I won't be insisting students learn.

Some other style updates:

• hand-washing (prediction, the hyphen form goes away quixkly
• "don't ask, don't tell" - settling the various uppercase/lowercase, quote/no-quote versions out there. However, I think after you use the quotes once in a story, you should be able to safely drop them on subsequent use. Otherwise, it can start looking like you're being snarky.
• check-in as noun and adjective, but checkout
  

And useful reminders that:

• The preferred term is dwarf because some people find midget offensive
• Iran is not an Arab country