Trap 000D (13) - General Protection Fault
A trap 000D is caused (but not limited to) when a program references storage outside the limit of the memory segment, references a storage segment that is restricted to privileged code, references storage with a selector value of zero, writing read-only memory or code segment, reading from an execute-only code segment or loading an invalid value into a selector register. [SYS1943]
NOTE: All protection violations which do not cause another exception cause a TRAP 000D.