Guardian Procedure Calls Reference Manual

In either case, the system name is returned in sysname.
The specified system does not exist.0
All paths to the specified system are down.-1
Bounds error occurred on sysname.-3
Considerations
When retrieving a line handler logical device number that exceeds 15 bits of magnitude:
GETSYSTEMNAME uses the number 32767 to represent any logical device number whose value
exceeds 15 bits of magnitude. (The value 32767 is reserved and is never used as an actual logical
device number.) To retrieve logical device numbers having more than 15 bits of magnitude, replace
calls to GETSYSTEMNAME with calls to NODENUMBER_TO_NODENAME_.
Example
LDEV := GETSYSTEMNAME( SYS^NUM ,SYS^NAME );
GETSYSTEMNAME Procedure (Superseded by NODENUMBER_TO_NODENAME_ Procedure) 673