MPARAM

A 4-byte message-dependent parameter structure

Type
void

C Declaration Method
typedef

Comment
Certain elements of information, placed into the parameters of a message, have data types that do not use all four bytes of this data type. The rules governing these cases are: BOOL  The value is contained in the low word and the high word is 0. SHORT The value is contained in the low word and its sign is extended into the high word. USHORT The value is contained in the low word and the high word is 0. NULL  The entire four bytes are 0. The structure of this data type depends on the message. For details, see the description of the particular message.