>I've seen OK long before before Okay. Supposedly Abraham Lincoln created OK from the initials of "Oll Korrect" but I don't believe it.

I've once (decades ago) read a story of an Irish barrelmaker O'Kaye, who signed each barrel once he was sure it would hold. He did it with just two characters, and the abbreviation was later applied to other things which were checked and proven to work. Then the usage spread.