The state of the conversation determines the type of APPCCMD, as denoted by the CONTROL and QUALIFY fields, that an application may issue. As the application issues APPCCMD macroinstructions, the state of the conversation changes. The change is a result of the function of the APPCCMD macroinstruction, a result of a verb issued by the remote transaction program, or a result of network errors.

The conversation state is defined in terms of the local application's view of the conversation. The states of other conversations allocated to the program can be different. For example, one conversation can be in RECEIVE state and another in SEND state, concurrently.

The conversation can be either a half-duplex conversation or a full-duplex conversation. Each of these two conversation types has its own set of possible states, with differing rules to allow transition from one state to another.

Descriptions of the possible conversation states for half-duplex conversations are located in Half-duplex conversation states. Possible conversation states for full-duplex conversations are described in Full-duplex conversation states.