Calls to External Routines

The Externref
The $ZCALL() Function
Externref vs. $ZCALL()

External calls permit access to functions implemented in other programming languages. GT.M supports external calls to any language that supports the VMS calling standard. GT.M also supports calls to M from an external routine that was itself called from M.

To access an external routine from GT.M you must:

Each of these steps is explained below, with the bulk of the chapter devoted to external call tables.

To understand external calls completely, you should have some knowledge of:

For more information, refer to the OpenVMS Calling Standard manual.