ONCOMERROR [branchLabel]

This sets or clears a branch label for handling errors when doing serial communications.  

    'to set a branch label for error handling
    oncomerror [myComErrorHandler]

    'to disable com error handling
    oncomerror

When an error does occur, three special variables will be set:

    ComError$      This holds a description of the error
    ComPortNumber  This holds the port number of the error
    ComErrorNumber   In the case of Win 95/98/ME this var is set to one of the Win16 com error codes, and in the case of Win NT/2K/XP OS error codes.


