Techniques for specification and verification of computer network protocols have progressed significantly in the past decade. The progress is largely due to the development of the state transition approach to formal specification and to the greater automation of the verification process. Some ISO state event protocols have been specified and verified using the state transition technique. However, this approach has not been used for a non-state event-driven type of protocol. The ISO JTM protocol contains procedures specifying where work is to be done in open systems; hence it is a procedural-oriented type of protocol. The paper presents a case study using a state transition technique, numerical Petri nets and an automated tool, PROTEAN, to specify and verify a procedural protocol, JTM.