Quoted from beelzeboob:...and you're thinking of ABACAB.
No - Abacab was named after the sections of the song bits Genesis was putting together. Another great band though!
Here is what I found about YYZ....
Title and composition
YYZ is the IATA airport identification code for Toronto Pearson International Airport, of Rush's native area of Toronto. It is common practice for air navigation aids to broadcast their identifier code in Morse code using VHF omnidirectional range (VOR). A plane using VOR equipment would then always know it's tracking the right station. The song's introduction, played in a time signature of 10/8 (not 5/4 as the eighth note clearly is receiving the beat, not the quarter note), repeatedly renders the letters "Y-Y-Z" in Morse Code using various musical arrangements.