Media: fiber optic, GLINK
Record Length: variable, depends on the number of reported clusters

19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
VRB START				Header Length								#Objects
				Header Format			Object Format					Object Length
				Tick								Data Type
				Turn
				FW Minor Version								FW Major Version
				Status Bits
				Cluster Object(s) : :
				Data Type								Tick
				Vertical Parity
				Pad Frame(s)
VRB END

Field Definitions

note: empty cells will contain zeros

VRB START     = "0101"
Header Length = 0x03
#Objects      = the number of Cluster Objects, range 0-48
Header Format = Header Format, "001"
Object Format = Object format, "00001"
Tick          = The accelerator bunch crossing number
Data Type     = varies with quadrant: CTQD0 = 0x82, CTQD1 = 0x83, CTQD2 = 0x84, CTQD3 = 0x85
Turn          = The accelerator turn (revolution) number
FW Minor Version = 0x00
FW Major Version = varies with the firmware version
Status Bits   = Reserved for diagnostic data

Cluster Objects are 32 bits long, which requires two frames in this record.
Bits [31:16] go into the first frame and bits [15:0] go into the second frame.
The 32 bits are defined as:

   [31]:    Track curvature bit
   [30:29]: Track PT bin ("00" = Max, "01" = High, "10" = Medium, "11" = Low)
   [28:26]: Extended PT information
   [25]:    Set to indicate a tight CPS cluster match
   [24]:    Loose CPS cluster match, unsupported and forced to "0"
   [23:21]: reserved, "000"
   [20]:    'R' bit. Set to indicate that the track matched to a CPS cluster outside the home sector
   [19:16]: "0000"
   [15:12]: The relative position of the cluster center within the home sector, range 0-15
   [11:9]:  Cluster width, in strips (7 = cluster width of 7 or wider)
   [8]:     Set to indicate that this cluster matched to an isolated track
   [7]:     Set to indicate that multiple tracks matched to this cluster
   [6:0]:   Trigger sector number, range 0-79

Vertical Parity = not supported, 0x0000
Pad Frame(s) = Pad frames are inserted in order to make the total record length
               a multiple of 8 frames. This requirement is imposed by the VRB hardware.
VRB END      = "1010"

Revision History

02 Nov 2005 : created JTO
03 Jan 2006 : added parity links JTO
05 Jan 2007 : reformat, no content changes JTO