It's more than just OS line ending issues: sometimes a logical record is more than one line. I've dealt with files in the past where the records consisted of several newline-terminated lines with a four character record separator along the lines of "EOR\n". chomp can handle removing this transparently (local $/ = "EOR\n"; while( <IN> ) { chomp; _handle_rec( $_ ) }), chop can't.
And that's the important distinction: chomp deals with removing the current logical record ending, chop deals with removing a single trailing character.
