Hey, all I did was use Wikipedia's interpretation. If either is right, I have no reason to argue one way or the other.
Topic on Talk:Telephone Exchange Names
Wikipedia is contradicting itself if it's turning TIdewater into TW. The counterexample from the same article is "MUrray Hill 5-9975 is another example of the 2L-5N format, one of the Ricardos' numbers on I Love Lucy. The H in Hill, although not dialed, is still capitalized as the first letter of the second word."
So MU5-9975 and not MH5-9975. Same comment on MUrray Hill as MU is confirmed by and .
Like I said, no argument. If I was repeating a wiki contributor's error, and you know better, more power to you.