Bracket and send/receive management
The change-direction and bracket indicators are used to begin, end, and control the direction of synchronous transmissions between a SLU P system and IMS.
IMS support of these indicators is summarized in the following table (X = supported).
| Synchronous transmissions | BB | EB | BB/EB | BB/CD |
|---|---|---|---|---|
| Received by IMS with data | X | X | X | |
| Sent by IMS with data | X | X | ||
| Received by IMS with data flow synchronous commands (normal flow) | X |
IMS does not support the absence of bracket indicators or the use of end-bracket-only on inbound synchronous data. IMS does not send output synchronous data with begin-bracket (BB) only, change-direction (CD) only, or BB/CD. Because IMS always ends a bracket (unconditional bracket termination) on input synchronous data, it is unnecessary to send either EB or CD on output synchronous commands. Input synchronous commands can specify EB or CD, but must be consistent with the current bracket and send/receive states; otherwise, the session is terminated. IMS does not send VTAM® indicators with data flow synchronous commands (normal flow).