Event_format


 The data from each event should be in YBOS format (see Table
 1).   Each event will typically consist of a number of banks
 for different types of data, possibly with associated  error
 banks (also in YBOS format).

 Each  of  the  data  banks  is  assigned  a   unique   name.
 Associated  with  each  data bank name is an error bank name
 (unless an error bank is never needed).   If  no  error  has
 occurred,  no error bank will be produced, and the data bank
 will appear alone.  If an error has occurred, an error  bank
 will  be  added  to the event.  In some cases, an error bank
 may occur without the associated data bank.  Only one  error
 bank of each name may appear per event, however there may be
 as many or more different error banks present in the  event,
 as  there  are types of data banks present.  Each error bank
 name is assigned a unique  bit  in  the  error_code_word  in
 BADD.

 The length of the event  is  the  total  length  (in  32-bit
 words) of all the banks for that event.




 TABLE 1
 Format of a YBOS bank


 WORD        CONTENTS
 -------------------------------------------------------------

 1    Name of bank (4 ASCII characters)
 2    Number of bank
 3    Index to next bank
 4    Exclusive length in words of the following datawords (ND)
 5    Type of bank
 6    ...............
 7    ...............
      Data for this event
      ...............
      etc.





 Data_buffer


 The data buffer (known as BDAT) will thus consist of a  list
 of events ordered in increasing event number (Table 2).  The
 length of BDAT will in general be different for every spill,
 depending  on the number of events collected, and the length
 of the individual events.


 TABLE 2
 Format of Data Buffer  BDAT


 WORD        CONTENTS
 ========================================================

 1    Exclusive length of BDAT (in 32-bit words)
 --------------------------------------------------------
 2    Start of data for event N
      .............                      EVENT N
      End of data for event N
 --------------------------------------------------------
      Start of data for event N+1
      .............                      EVENT N+1
      End of data for event N+1
 --------------------------------------------------------
      etc.



 Address_buffer


 Associated with BDAT is an address buffer BADD (see Table 3)
 that  contains  four  words  for  each event stored in BDAT.
 BADD also is of variable length.   Thus  if  20  events  are
 contained in BDAT, the length of BADD would be 80 words.


 TABLE 3
 The format of the address buffer BADD



 WORD        CONTENTS
 =========================================================
 1    Event number of event N
 2    Length (in 32-bit words) of event N        EVENT N
 3    Address in BDAT of start of event N
 4    Error code word for event N
 ---------------------------------------------------------
 5    Event number of event N+1
 6    Length (in 32-bit words) of event N+1      EVENT N+1
 7    Address in BDAT of start of event N+1
 8    Error code word for event N+1
 ---------------------------------------------------------
 9    etc.

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