! Columbus supports keywords that override observation standard deviations defined in observation 
! records. When one of the following keywords is encountered, the standard deviation (or variance 
! where applicable) defined in the keyword, will replace the current standard deviation (or variance) 
! in the observation.

! Example:

! Establish a standard deviation of 10 seconds for all azimuth observations declared after 
! the _G_AZ_SD record.

_G_AZ_SD; 10

! Azimuth observation set with azimuth standard deviation of 0.1 seconds.
_OBS_AZ_SET; AAA; BBB; 120.0000; 0.1; NOOBS; NOOBS; NOOBS; NOOBS; 0.0; 0.0

! When the above azimuth observation is read, the standard deviation applied to it will be 
! 10 seconds (not 0.1 seconds)

! Turn the override off (for all azimuth observations that follow) by setting _G_AZ_SD to zero.
_G_AZ_SD; 0




_G_AZ_SD; 5.0
! Azimuth standard deviation override set to 5 seconds.


_G_GEODESIC_AZ_SD; 2.0
! Geodesic azimuth standard deviation override set to 2 seconds.


_G_DIR_SD; 5.0
! Direction standard deviation override set to 5 seconds.


_G_BEAR_SD; 5.0
! Direction standard deviation override set to 5 seconds.


_G_HA_SD; 2.0
! Horiz angle standard deviation override set to 2 seconds.


_G_ZEN_SD; 15.0
! Zenith angle standard deviation override set to 15 seconds.


_G_CHORD_SD; 0.003
! Chord (slope distance) standard deviation override set to 0.003 active linear units. 


_G_HOR_DIST_SD; 0.007
! Horiz distance standard deviation override set to 0.007 active linear units. 


_G_HGTDIFF_SD; 0.002
! Height difference standard deviation override set to 0.002 active linear units. 


_G_DN_SD; 0.004
! Delta north standard deviation override set to 0.004 active linear units. 


_G_DE_SD; 0.004
! Delta east standard deviation override set to 0.004 active linear units. 


_G_DUP_SD; 0.004
! Delta up standard deviation override set to 0.004 active linear units. 


_G_GEODESIC_SD; 0.0025
! Geodesic distance standard deviation override set to 0.0025 linear units.


_G_X_SD; 0.005
! GPS delta X standard deviation override set to 0.005 linear units. This
! setting will automatically set non-diagonal correlation elements to 0.0.


_G_Y_SD; 0.004
! GPS delta Y standard deviation override set to 0.004 linear units. This
! setting will automatically set non-diagonal correlation elements to 0.0.


_G_Z_SD; 0.007
! GPS delta Z standard deviation override set to 0.007 linear units. This
! setting will automatically set non-diagonal correlation elements to 0.0.


_G_X_VAR; 0.00003
! GPS delta X variance override set to 0.00003 linear units. This setting 
! will automatically set non-diagonal covariance elements to 0.0.


_G_Y_VAR; 0.00003
! GPS delta Y variance override set to 0.00003 linear units. This setting 
! will automatically set non-diagonal covariance elements to 0.0.


_G_Z_VAR; 0.00006
! GPS delta Z variance override set to 0.00006 linear units. This setting 
! will automatically set non-diagonal covariance elements to 0.0.


_G_LAT_SD; 0.004
! Latitude coordinate observation standard deviation override set to 0.004 
! linear units. This setting will automatically set non-diagonal correlation 
! elements to 0.0.


_G_LON_SD; 0.005
! Longitude coordinate observation standard deviation override set to 0.005 
! linear units. This setting will automatically set non-diagonal correlation 
! elements to 0.0.


_G_HGT_SD; 0.008
! Height coordinate observation standard deviation override set to 0.008 
! linear units. This setting will automatically set non-diagonal correlation 
! elements to 0.0.


_G_LAT_VAR; 0.00033
! Latitude coordinate observation variance override set to 0.00033 linear 
! units. This setting will automatically set non-diagonal covariance elements 
! to 0.0.


_G_LON_VAR; 0.00035
! Longitude coordinate observation variance override set to 0.00035 linear 
! units. This setting will automatically set non-diagonal covariance elements 
! to 0.0.


_G_HGT_VAR; 0.00044
! Height coordinate observation variance override set to 0.00044 linear 
! units. This setting will automatically set non-diagonal covariance elements 
! to 0.0.


_G_NORTH_SD; 0.004
! North coordinate observation standard deviation override set to 0.004 
! linear units. This setting will automatically set non-diagonal correlation 
! elements to 0.0.


_G_EAST_SD; 0.007
! East coordinate observation standard deviation override set to 0.007 
! linear units. This setting will automatically set non-diagonal correlation 
! elements to 0.0.


_G_NORTH_VAR; 0.00030
! North coordinate observation variance override set to 0.00030 linear 
! units. This setting will automatically set non-diagonal covariance elements 
! to 0.0.


_G_EAST_VAR; 0.00045
! East coordinate observation variance override set to 0.00045 linear 
! units. This setting will automatically set non-diagonal covariance elements 
! to 0.0.