When the HP-3000 compatibility option is enabled, the software switches SW0 thru SW15 are supported. SW0 thru SW8 are aliases for SWITCH-0 thru SWITCH-8. SW9 thry SW15 are additional switches.
Switches are set by setting the environment variable COBSWITCH to a string of '0' and '1'. SW0 is represented by the left-most digit, proceding to the right for higher numbered switches.
see also Switch name clause