Call letter designation question

[Bob Nelson]

Sometimes I'll see something in the paper like this:
The Red Sox game will be on "WEEI-AM (850)" (sic)

I thought that AM stations were technically just the
call letters

WRKO
WFAN
WABC (etc)

...and FM stations were designated by the suffix -FM
ONLY if there is already an AM with those calls

WCBS-FM (since there IS a WCBS)
WBCN (since there is, as far as I know, no WBCN on the
AM dial)

On 100000watts.com I saw the following listing for
WRMR in Cleveland:

"(changed calls from) WCLVAM to WRMRAM on 1/1/2003)"
(sic)

Is that correct? Referring to AM stations that way?

I would think that if, say, a newspaper were to
mention an AM station and point out their frequency as
well, they could do it thusly:

"WEEI (AM) 850" or "WEEI (AM 850)"
instead of "WEEI-AM (850)"...

(Of course, I've seen some papers with
misprints...like this one:)

Red Sox vs. Twins, WEEI-FM (850) (sic)
"Darn it! I just can't find 850 on my FM dial!" :)

Hint: the paper in question is on Morrissey Blvd.,
right near Ch. 56 and Greater Media :)