"The first 128 subroutines defined in your script are special: these subroutines can be started using a serial or native USB command, and each call from within your script requires only one byte of script space."
This is taken from the Maestro Users Manual. It also states that the number of subroutines is unlimited.
I now have a Mini Maestro 24 in use which has 72 subroutines in its program. 63 is the last subroutine that it will run either from its program or from a serial command. Can some one confirm that the manual is correct as I have tried two of these units and neither will go past that 64 mark, 0 to 63. Any attempt to run 64 on just hangs the unit.
Firmware is 1.00 by the way but the write up on 1.01 does not have any mentiopn of this. Without these subroutines the Maestro is useless to my project.
Dougie L 
David, you have saved a years work !. I have been slowly adding the ability to do further control of my garden railway terminus to the Pololu Maestro. I had not thought to check for any updates before as it worked till a couple of days ago. I added another ten subroutines that pushed it past that 64 mark and got very frustrated when it failed to work.