Specifications of HARPOS format version of 2005.03.28
   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
   HARPOS format is for describing site displacements which can
be represented by a finite set of harmonic components.
 
   A file in HARPOS format consists of records of variable length in
ASCII coding. The records are separated by a character with decimal
code 13. The records of the following types are supported:
 
1) Header record;
2) Harmonic definition records;
3) The radius of the area of applicability;
4) Site definition records;
5) Displacement definition records;
6) Trailer record.
 
   Records which start from # character are considered as comments.
 
   Each valid file in HARPOS format has the first header record, one
or more harmonic definition records, one or more site definition
records and one or more displacement definition records. The last
record is a trailer record. All harmonic definition records should
precede site definition records. All site definition records should
precede displacement definition records.
 
   Records format:
 
1) A header record contains the string
   "HARPOS Format version of 2005.03.28"
 
   The header record allows to distinguish the valid file in the
   HARPOS format from files in other formats.
 
2) A harmonic definition record defines the argument of the harmonic in
   the form {phase + freq*(t-t0) + 1/2*accel*(t-t0)**2}  where t is
   time in TDT time scale and t0 is the reference epoch J2000.0,
   01 January 2000, 12 hours TDT. The file cannot contain more than one
   definition of the same harmonic.
 
Format of an H-record:
----------------------
 
Field  1:1   A1     -- Records ID: letter H (decimal code 72).
field  2:3   a2     -- delimiters: blanks.
Field  4:11  A8     -- 8-letter long harmonic name. May contain any
                       characters with decimal codes 32-255, but blanks
                       are allowed only at the end of the harmonic name.
                       This field should not necessarily have a special
                       meaning. Parsing software should not try to
                       interpret this name.
field 12:13  a2     -- delimiters: blanks.
Field 14:26  D13.6  -- Phase of the harmonic in float format.
                       Units: rad.
field 27:28  a2     -- delimiters: blanks.
Field 29:47  D19.12 -- Frequency of the harmonic in float format.
                       Units: rad/sec.
field 48:49  a2     -- delimiters: blanks.
Field 50:59  D10.3  -- Acceleration of the harmonic in float format.
                       Units: rad/sec**2.
field 60:80  a21    -- delimiters: blanks.
 
3) An applicability record defines the radius of the area for which
   information about displacements is valid. D-record defines displacement
   for the area around a station. This area is called "site". Displacement
   for the site is applicable to any point (station) located within 
   a disk around the site with the radius specified in this record

Format of an A-record:
----------------------

Field  1:1   A1     -- Record ID: letter A (decimal code 65).
field  2:3   a2     -- delimiters: blanks.
Field  4:17  F14.6  -- Radius of the site area in meters

4) A site definition record defines the site identifier and site
   coordinates in a crust-fixed reference frame. The file cannot
   contain more than one definition of the same site.
 
Format of an S-record:
----------------------
 
Field  1:1   A1     -- Record ID. Should be letter S (decimal code 83)
Field  2:3   A2     -- Delimiters: blanks.
Field  4:11  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 site identifier should be
                       unique among S-records. This field should not
                       necessarily have a special meaning. Parsing
                       software should not try to interpret it.
field 12:13  a2     -- delimiters: blanks.
Field 14:26  F13.4  -- Site X coordinate in a crust fixed reference
                       frame. Units: meters.
field 27:27  a1     -- delimiters: blanks.
Field 28:40  F13.4  -- Site Y coordinate in a crust fixed reference
                       frame. Units: meters.
field 41:41  a1     -- delimiters: blanks.
Field 42:54  F13.4  -- Site Z coordinate in a crust fixed reference
                       frame. Units: meters.
field 55:56  a2     -- delimiters: blanks.
Field 57:64  F8.4   -- Site geocentric latitude, positive to north,
                       in degrees. This field is for information only.
                       Parsing software MUST ignore it.
field 65:65  a1     -- delimiters: blanks.
Field 66:73  F8.4   -- Site longitude, positive towards east,
                       in degrees. This field is for information only.
                       Parsing software MUST ignore it.
field 74:74  a1     -- delimiters: blanks.
Field 75:80  F6.1   -- Site height above the reference ellipsoid
                       in meters. This field is for information only.
                       Parsing software MUST ignore it.
 
5) A data record specifies the site, the harmonic and 6 amplitudes of
   displacements: Up cosine, East cosine, North cosine, Up sine,
   East sine, North sine. A file cannot contain more than one data
   record for the same harmonic, the same site. The site and the
   harmonic referred in a data record must be defined in the preceding
   site and harmonic definition records.
 
   Notation "Up cosine" and "Up sine" amplitudes of the displacement
   means that the radial component of the topocentric vector of the
   displacement, which is parallel to the vector from the geocenter to
   the site, depends on time in the following way:
 
   D_up= Ampl_cos_up * cos {phase + freq*(t-t0) + 1/2*accel*(t-t0)**2} +
         Ampl_sin_up * sin {phase + freq*(t-t0) + 1/2*accel*(t-t0)**2}
 
   Analogously, "East cosine", "East sine" amplitudes define time
   dependence of the east component of the displacement vector, and
   "North cosine", "North sine" define time dependence of the north
   component.
 
Format of a D-record:
---------------------
 
Field  1:1   A1     -- Record ID: letter D (decimal code 68).
field  2:3   a2     -- delimiters: blanks.
Field  4:11  A8     -- 8-letter long harmonic name. The harmonic name
                       must be defined in a preceding H-record.
field 12:13  a2     -- delimiters: blanks.
Field 14:21  A8     -- 8-letter long site identifier. The site
                       identifier must be defined in a preceding
                       S-record.
field 22:24  a3     -- delimiters: blanks.
Field 25:32  F8.5   -- Cosine amplitude of the Up component of the
                       displacement vector. Up direction is along the
                       vector from the geocenter to the site.
                       Units: meters.
field 33:33  A1     -- delimiter: blank.
Field 34:41  F8.5   -- Cosine amplitude of the East component of the
                       displacement vector. Units: meters.
field 42:42  a1     -- delimiter: blank.
Field 43:50  F8.5   -- Cosine amplitude of the North component of the
                       displacement vector. Units: meters.
field 51:53  a3     -- delimiter: blanks.
Field 54:61  F8.5   -- Sine amplitude of the Up component of the
                       displacement vector. Up direction is along the
                       vector from the geocenter to the site.
                       Units: meters.
field 62:62  a1     -- delimiter: blank.
Field 63:70  F8.5   -- Sine amplitude of the East component of the
                       displacement vector. Units: meters.
field 71:71  a1     -- delimiter: blank.
Field 72:79  F8.5   -- Sine amplitude of the North component of the
                       displacement vector. Units: meters.
field 80:80  a1     -- delimiter: blank.
 
 
6) Trailer record is the same as the header record.