You can code a model application program definition, which can be used as the definition for one or more VTAM® application programs. You code a model application program definition by placing wildcard characters in the name field of an APPL definition statement that defines characteristics for one or more application programs.

If VTAM cannot find an active definition for the application program associated with the ACB specified on an OPEN macroinstruction, it searches a list of model definitions to find a name that best matches the name of the application program associated with the ACB. If it finds a match, it uses that definition statement to define the application program. If it does not find a match, it returns an error condition indicator to the application program.

An application program that is built from a model application program definition is called a dynamic application program, a clone application program, or a replicated application program.

Model application program definitions enable you to reduce the number of application program definitions you must code in VTAMLST.

You can use model application program definitions in nonsysplex and sysplex environments. The value of using them, however, is most apparent in sysplex environments.

In a sysplex environment, model application program definitions can be contained in a single VTAMLST accessible to all VTAMs in the sysplex. An application program can open its ACB on any VTAM in the sysplex. In addition, an application program can be moved to any VTAM in the sysplex by closing its ACB on one VTAM and opening it on another.