StrucId (MQCHAR4)

This is the structure identifier, and must be:

MQMD_STRUC_ID: Identifier for message descriptor structure.
For the C programming language, the constant MQMD_STRUC_ID_ARRAY is also defined; this has the same value as MQMD_STRUC_ID, but is an array of characters instead of a string.

This is always an input field. The initial value of this field is MQMD_STRUC_ID.