anchor.diff:  Mark,Operator,Agency,Model,Satellite System,Interval,Elevation Mask,Header Comment,Format,Start Date,End Date
  -2406,GeoNet,GNS,TRIMBLE NETR9,GPS+GLO,30s,4,geonet,trimble_netr9 x4,2012-02-13T00:38:01Z,2015-03-09T00:50:00Z
  +2406,GeoNet,GNS,TRIMBLE NETR9,GPS+GLO,30s,3,geonet,trimble_netr9 x4,2012-02-13T00:38:01Z,2015-03-09T00:50:00Z
   2406,GeoNet,GNS,TRIMBLE NETR9,GPS+GLO,30s,0,geonet,trimble_netr9 x4,2015-03-09T00:50:01Z,9999-01-01T00:00:00Z
   AHTI,GeoNet,GNS,TRIMBLE NETRS,GPS,30s,4,geonet,trimble_5700 x4,2009-06-10T23:31:00Z,2015-12-07T02:04:37Z
   AHTI,GeoNet,GNS,TRIMBLE NETR9,GPS+GLO,30s,0,geonet,trimble_netr9 x4,2015-12-07T02:04:38Z,9999-01-01T00:00:00Z
   AKTO,GeoNet,GNS,TRIMBLE NETRS,GPS,30s,4,geonet,trimble_5700 x4,2006-04-27T00:01:01Z,2015-10-01T20:10:00Z
   AKTO,GeoNet,GNS,TRIMBLE NETR9,GPS+GLO,30s,0,geonet,trimble_netr9 x4,2015-10-01T21:39:00Z,9999-01-01T00:00:00Z
  -ANAU,GeoNet,GNS,TRIMBLE NETR9,GPS+GLO,30s,4,geonet,trimble_netr9 x4,2010-10-18T23:35:01Z,2015-09-03T04:13:00Z
  +ANAU,GeoNet,GNS,TRIMBLE NETR9,GPS+GLO,30s,4,geonet,trimble_netr9 x4,2010-10-18T23:35:01Z,2010-12-21T01:40:00Z
  +ANAU,GeoNet,GNS,TRIMBLE NETR9,GPS+GLO,30s,3,geonet,trimble_netr9 x4,2010-12-21T01:40:01Z,2015-09-03T04:13:00Z
   ANAU,GeoNet,GNS,TRIMBLE NETR9,GPS+GLO,30s,0,geonet,trimble_netr9 x4,2015-09-03T04:13:01Z,9999-01-01T00:00:00Z
   ARTA,GeoNet,GNS,TRIMBLE NETRS,GPS,30s,4,geonet,trimble_5700 x4,2008-11-05T00:00:00Z,2016-03-21T22:28:59Z
   ARTA,GeoNet,GNS,TRIMBLE NETR9,GPS+GLO,30s,0,geonet,trimble_netr9 x4,2016-03-21T22:29:02Z,9999-01-01T00:00:00Z
  
positive.code: VGOT,GeoNet,GNS,TRIMBLE NETR9,GPS+GLO,30s,0,geonet,trimble_netr9 x4,2017-02-21T21:22:32Z,9999-01-01T00:00:00Z
  VGPK,GeoNet,GNS,TRIMBLE NETRS,GPS,30s,4,geonet,trimble_5700 x4,2005-01-21T00:00:00Z,2016-08-23T01:10:31Z
  VGPK,GeoNet,GNS,TRIMBLE NETR9,GPS+GLO,30s,0,geonet,trimble_netr9 x4,2016-08-23T01:10:33Z,9999-01-01T00:00:00Z
  VGT2,GeoNet,GNS,TRIMBLE NETR9,GPS+GLO,30s,4,geonet,trimble_netr9 x4,2012-07-27T01:00:00Z,2012-08-06T11:50:00Z
  VGT8,GeoNet,GNS,TRIMBLE NETR9,GPS+GLO,30s,3,geonet,trimble_netr9 x4,2013-06-10T03:05:34Z,2016-04-27T23:32:25Z
  VGT8,GeoNet,GNS,TRIMBLE NETR9,GPS+GLO,30s,0,geonet,trimble_netr9 x4,2016-04-27T23:32:26Z,2016-05-09T13:00:00Z
  VGTM,GeoNet,GNS,TRIMBLE NETR9,GPS+GLO,30s,3,geonet,trimble_netr9 x4,2013-05-14T23:00:00Z,2016-04-22T02:28:33Z
  
negative.code: MCNL,GeoNet,GNS,TRIMBLE NETRS,GPS,30s,4,geonet,trimble_5700 x4,2008-05-27T00:05:00Z,2018-05-22T05:33:37Z
  MCNL,GeoNet,GNS,TRIMBLE NETR9,GPS+GLO,30s,0,geonet,trimble_netr9 x4,2018-05-22T05:33:38Z,2019-10-03T01:07:59Z
  MCNL,GeoNet,GNS,TRIMBLE ALLOY,GPS+GLO,30s,0,geonet,trimble_netr9 x4,2019-10-03T01:08:00Z,9999-01-01T00:00:00Z
  METH,GeoNet,GNS,TRIMBLE NETR9,GPS+GLO,30s,4,linz,trimble_netr9 x4,2010-10-12T00:24:01Z,2010-12-21T01:40:00Z
  METH,GeoNet,GNS,TRIMBLE NETR9,GPS+GLO,30s,3,linz,trimble_netr9 x4,2010-12-21T01:40:01Z,2014-07-27T21:49:59Z
  METH,GeoNet,GNS,TRIMBLE NETR9,GPS+GLO,30s,0,linz,trimble_netr9 x4,2014-07-27T21:50:44Z,2016-04-11T17:09:37Z
  METH,GeoNet,GNS,TRIMBLE NETR9,GPS+GLO+GAL+BDS+QZSS,30s,0,linz,trimble_netr9 x4,2016-04-11T17:09:38Z,2019-09-19T01:15:31Z
  METH,GeoNet,GNS,TRIMBLE ALLOY,GPS+GLO+GAL+BDS+QZSS,30s,0,linz,trimble_netr9 x4,2019-09-19T01:15:32Z,9999-01-01T00:00:00Z
  