# DS_MSG_HEADER

Message header.

### Synopsis

    #define DS_MSG_HEADER
    long whatToDo;
    Item msgItem;
    void* privatePtr;
    void* link;

### Description

A standard set of fields appearing at the beginning of messages sent from the streamer to subscribers. The fields enable a couple of utility routines to perform general operations on lists.

### Fields

`whatToDo`
  Opcode determining message contents.

`msgItem`
  Message item for sending this buffer.

`privatePtr`
  Pointer to sender's private data.

`link`
  User defined - for linking message into lists.

### Associated Files

DSStreamHeader.h