The full Vapor-M specification: here.
Though the full specification defines many built-in operations, for your homework you are only allowed to use the following:
The full specification allows computed goto instructions, where the target address is specified by a register. For your homework, goto can only refer to code labels.
The full specification allows strings everywhere. For your homework, strings are only allowed as arguments to the Error built-in.
The register $t9 is reserved for the next assignment.