Complex sentence: The 2001 Clear Channel memorandum is a controversial document distributed by Clear Channel Communications to the over 1,200 radio stations they owned, shortly after the September 11,2001 attacks, containing a list of a large number of what the memo termed "lyrically questionable" songs.
Split into simpler sentences: The 2001 Clear Channel memorandum is a controversial document distributed shortly after the September 11,2001 attacks by Clear Channel Communications to the more than 1,200 radio stations they owned. The memo contained a long list of what the memo termed "lyrically questionable" songs.