type:  txt 
allowed: echo "v1 v2 all"
default:  "v2"
syntax:expression: $VAR(@) in "v1", "v2", "all" ;
	"Invalid SSH protocol version"

help: SSH protocol version
val_help: v1; Protocol version 1 (UNSECURE DO NOT USE)
val_help: v2; Protocol version 2 (default)
val_help: all; Both version 1 and version 2 supported