Yahoo Answers - "What do the letters in a Radio Stations & TV name stand for? Who picks the letters?"

After Yahoo mentioned this issue on their home page, and after I admit that I was looking for the answer of this question, we clicked on this yet-to-be a trivial question's answer.

According to the answer posted, people are free to choose whatever combination they want to choose and also they need to stay with the rule of:
"in the 1930's, the US established W stations on the East Coast and K on the West Coast (divided roughly at the Mississippi River.)"

I could not find an answer for this question in Wikipedia, but Yahoo "answers," indeed.