Hello, I am trying to extend nonposArgs to include more checks and I am having a hard time. I have gotten basic checks working, but I am not able to get some of the more complicated checks working. The tutorial shows that the syntax for extending nonposArgs is: *someobject|someclass* *proc|instproc* methodName {?optional arguments? argName args} { ... } I have not been able to get the ?optional arguments? to work. Example: I am trying to get some checks done that will check for specific values of the Arg. I would like to be able to pass those values into the check. xotcl::nonposArgs proc RANGE {allowedRange argName args} { .....code to verify the range } The syntax to use this would be similar to: Class Foo Foo instproc setMtu {{-mtu:RANGE 54-65535 "1500"}} {} { .... } This is similar to what Giovannni Cristelli asked in the post titled XOTcl extending nonPosArgs class from November 2004. Is there any way to do this currently? I am trying to replace a bloated package that is currently being used which has many of these checks available. I have tried many combinations of syntax to get this to work and have not been able to figure it out. Thanks, Shawn