GO tells VISTA to start executing the procedure held in its procedure buffer. You may also supply parameters to the procedure on the command line. The parameters must be evaluated using the PARAMETER command in the procedure.
Earlier versions of VISTA allowed you to specify a number of times to execute a procedure, as in 'GO 3', which executed the current procedure three times. This was installed in the earliest versions of VISTA, before there were DO loops. This feature has been deleted from the version 3. The old version 2 form 'GO filename' has been eliminated, since this can now be done with the CALL command.