ApplIdentityData is information that is defined by the application suite, and can be used to provide additional information about the message or its originator. The queue manager treats this information as character data, but does not define the format of it. When the queue manager generates this information, it is entirely blank.
For the MQPUT and MQPUT1 calls, this is an input/output field if MQPMO_SET_IDENTITY_CONTEXT or MQPMO_SET_ALL_CONTEXT is specified in the PutMsgOpts parameter. If a null character is present, the null and any following characters are converted to blanks by the queue manager. If neither MQPMO_SET_IDENTITY_CONTEXT nor MQPMO_SET_ALL_CONTEXT is specified, this field is ignored on input and is an output-only field. For more information about message context, see Message context.
After the successful completion of an MQPUT or MQPUT1 call, this field contains the
ApplIdentityData that was transmitted with the message if it was put to a queue. This will be the value of
ApplIdentityData that is kept with the message if it is retained (see description of MQPMO_RETAIN for more details about retained publications) but is not used as the
ApplIdentityData when the message is sent as a publication to subscribers because they provide a value to override
ApplIdentityData in all publications sent to them. If the message has no context, the field is entirely blank.
This is an output field for the MQGET call. The length of this field is given by MQ_APPL_IDENTITY_DATA_LENGTH. The initial value of this field is the null string in C, and 32 blank characters in other programming languages.