Signatures

Signatures describe the messages that the program wants to receive. A signature is divided by an arrow (=>) into two parts. The first part of a signature specifies matching attribute values. The more attribute values specified in a signature, the fewer messages the signature will match. The second part of a signature specifies receiver values that the ToolTalk service will copy into messages that match the first part of the signature.

A ptype signature can contain values for disposition and operation numbers (opnum). The ToolTalk service uses the disposition value (start, queue, or the default discard) to determine what to do with a message that matches the signature when no process is running the program. The opnum value is provided as a convenience to message receivers. When two signatures have the same operation name but different arguments, different opnums makes incoming messages easy to identify.