********  The g-2 data format (preliminary)  ********************

1) General structure:

                Event header (6*4 bytes)
          Electronics id (2 bytes)  sub detector evt size (2 bytes)
                data
          Electronics id (2 bytes)  sub detector evt size (2 bytes)
                data
                ......

2) Event header

             word 0:   Total event length in 32 bit words, including header
             word 1:   record type:
                           0:   event record
                           1:   begin record
                           2:   pause record
                           3:   resume record
                           4:   end record
             word 2:   run number
             word 3:   event number
             word 4:   run mode
                           0:  beam
                           1:  flight simulator
                           2:  pseudo
             word 5:   unused

3) Electronics id

     bit:  31-30   spare              (0)
           29-28   data format        (0)
           27-20   sequential number (1-12)
           19-16   electronics type
                     MTDC:    1   (0001)
                     WFD:     2   (0010)
                     FastBus: 3   (0011)
                     CAMAC:   4   (0100)
                     PSD:     8   (1000)
           15-0    data size in 32 bit words (including header word)


4) MTDC data buffer
        A list of 32-bit words, all of the following format:
        bit: 31-12    time
             11-8     error/parity
              7-3     channel id
                2     pulse edge
                1     synchronization error
                0     unused
5) WFD data buffer
           32-bit daughter-header
                bit 17   daughter board (0 == top, 1 == bottom)
                bit 16    phase 
                bit 0-15  event length (==X)
           X/2 32 bit ADC words, each byte of which is an ADC-value during
                5 ns.  (0-255, 255== 1V)
           X/2 32-bit time/discriminator  words
                bits 31-16 == time 
                bits 15-0 == discr. info (ask Rob)
           All of this 4 times for one WFD

6) PSD data buffer
7) FastBus data buffer
8) CAMAC data buffer

**********  WFD data structure    ***********************

Data from each WFD input channel is stored on separate memory locations. The
WFD buffers have the following format:

      WFD 

**********  MTDC data structure   ***********************


********* DAQ additions to the data *******************

Since i/o is the limiting factor, the DAQ should only add a minimal
amount of information to the data. This information should 
provide for each 'sub-detector':
1) a means to identify the data source WFD/MTDC/others
2) a means to relate data to detector stations
3) the data format (future: compression/reduction)
4) the 'sub-detector' size

Each event should have an header containing info as:
1) run number
2) event number
3) date
4) trigger type
5) run mode
The standard UNIDAQ header consits of 6 long words which gives us some
spares.

By just adding these minimal additions, the buffers from MTDC and WFD
will not have to be decoded on-line. Only when using data compression 
does the online have to touch the buffers. This guards the data against
possible decoding bugs.