   Specifications of BINDISP  format version of 2019.12.28
   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

   BINDISP format is for describing time series of site position 
variations. A file in this format contains three components of the 
displacement vector of a specific site equally sampled within 
a certain time range.

   A file consists of records of fixed length. Record length is 
8 bytes. A file has 44 header records and at least one data record 
which follows header records.

Header record 1:
----------------

Field  1:8  A8   -- Unix magic record. Should be "BINDISP " for  
                    a valid file.

Header record 2:
----------------

Field 1:4   I*4  -- Integer modified Julian of the format 
                    revision date.
Field 5:5   A1   -- Identifier for used binary integer format.
                    Supported identifiers:
                    B -- big endian format
                    L -- little endian format
Field 6:6   A1   -- Identifier for used binary float format.
                    Supported identifiers:
                    I -- IEEE 754/854 format.
                    D -- Dec format.
Field 7:8   I*2  -- Reserved. filled with binary value 0.


Header record 3:
----------------

Field 1:8   A8   -- 8-letter long site identifier. May contain 
                    any characters with decimal codes 32-255, but 
                    blanks are allowed only at the end of the site 
                    identifier. This field should not necessarily 
                    have a special meaning. Parsing software should
                    not try to interpret it.

Header record 4:
----------------

Field 1:4   I*4  -- The total number of data records.
Field 5:8   R*4  -- Sampling interval in seconds: the interval
                    between two consecutive epochs.

Header record 5:
----------------

Field 1:8   R*8  -- X site coordinate in a crust fixed reference 
                    frame. Units: meter.

Header record 6:
----------------

Field 1:8   R*8  -- Y site coordinate in a crust fixed reference 
                    frame. Units: meter.

Header record 7:
----------------

Field 1:8   R*8  -- Z site coordinate in a crust fixed reference 
                    frame. Units: meter.

Header record 8:
----------------

Field 1:4   I*4  -- Integer modified Julian data at the midnight
                    of the time epoch of the first data record.
Field 5:8   R*4  -- Time in TDT elapsed from the midnight of
                    the time epoch of the first data record,
                    in seconds.

Header record 9:
----------------

Field 1:8   C*8  -- Model type

Header record 10:
-----------------

Field 1:8   C*8  -- Model name

Header record 10:
-----------------

Field 1:8   C*8  -- Model version


Header records 11 to 44:
------------------------

Field 1:8   C*8  -- Comment


Data record:
============

Displacement is endcoded as a sum of the base displacement and 
extension. Total extension is computed as 
total = 1.0D-5 * base + 0.32D0 * sign(base)*extension
The total displacement can be in a range [-5.44, 5.44] meters.

Field 1:2   I*2  -- 1.0D-5 singed base X coordinate of site displacement 
                    for a given epoch in a crust-fixed reference system. 
                    Units: 1.D-5 meter.

Field 3:4   I*2  -- base Y coordinate of site displacement without extension
                    for a given epoch in a crust-fixed reference system. 
                    Units: 1.D-5 meter.

Field 5:6   I*2  -- base Z coordinate of site displacement without extension
                    for a given epoch in a crust-fixed reference system. 
                    Units: 1.D-5 meter.

Field 7:8   I*2  -- Bit fields of extension. The word is split into four
                    bit fields of 4 bits each.
                    bits  0:3  -- reserved
                    bits  4:7  -- unsigned extension for X coordinate
                    bits  8:11 -- unsigned extension for Y coordinate
                    bits 12:15 -- unsigned extension for Z coordinate

  Comments:

  1. Data records follow in chronological order. No records can be 
     missed. The epoch of the J+1 th record is the epoch of the 
     J -th record plus the sampling interval. The epoch of the K-th 
     physical record of the file is (MJD,TDT) + (K-9)*Sample_interval. 
     Physical records are counted from 1.

  2. Maximal displacements in site positions which can be described  
     in this file cannot exceed by modulo 5.4 meters.
