trumpet blower88

I've been wondering for a while now about all the differant laws regarding copyrights, and I found a website last night that answerd a few of my questions, but it's only made me wonder more about the questions it didn't answer.

Regarding Choral works, it talked about the rights required when adding text, like someone elses poems. It came us with these 3 rules:

-Works first published before 1923 are in the public domain in the United States (but may be protected in other countries if the author is not a U.S. national).

-Works first published from 1923 through 1977 are protected in the United States for a term of 95 years (assuming they complied with certain formalities).

-Works written after 1978 are protected for the life of the author plus seventy years.


This got me wondering about band and orchestral music. Are the laws pretty much the same as above, or is it differant? I've found hundreds of differant arrangments of Pachabells Cannon in D, and I'm pretty sure not half of them took the time to obtain the rights to that. So would a piece like this, written so long ago (or before 1923) be in the Public Domain and free for anyone to use, or do you have to get permission from the rights holder? I can't find anywhere where it talks about what is and what isn't in the public domain, does anyone here know of anything that can tell me what and what isn't free for anyone to use?

__________________
-David Jacques