Jon Udell at O'Reilly Radar – Heds, deks, and ledes:

"When a copy editor applies a real or virtual red pencil to a piece of journalistic prose, he or she is likely to use weird spellings: hed for head (headline), dek for deck (subhead), lede for lead (first paragraph). The idea is that these intentional misspellings will help distinguish an editor's commentary from a writer's prose.

Whether this is a useful convention or just an antiquated habit I really can't say. But the principle of heads, decks, and leads matters more than ever, and not just in journalism."

Now I finally understand why the NITF standard uses "hedline" instead of "headline"…