tree and tabular combined notation (ATM) (TTCN)

Tree and Tabular Combined Notation (TTCN) is an internationally standardized test script notation for protocol testing. TTCN provides a notation that is independent of the test method, layers, and protocols.

The TTCN notation has a mechanism to represent time-related states of a network protocol using the Finite State Machine (FSM) in a tree structure. Activities for the Tree and Tabular Combined Notation started in the 1990s by the International Standards Organization( ISO) and the IEC. TTCN is standardized as ISO standard 9646.

TTCN is used to describe the timing of events or tests. Such a test is used to test communicating systems. The abstract syntaxASN.1 is used to describe the data in TTCN.