Paul, that does sound right. The rules have changed over the years.
For example, when the first musical won ("Of Thee I Sing!"), they only gave the award to the book writer and lyricist. So, good old George Gershwin didn't get an award. The reasoning was that this was a "literary" award, so it was all about the words, both spoken and sung. But it wasn't for the music.
Ira Gershwin was so upset that he publicly took the award and gave it to his brother George. They have since changed the rule to include the composer, if a musical should win, and I believe they now credit George with having won the award, even though he didn't, initially.
"Jaws is the Citizen Kane of movies."
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