## GENC: Generate Covariance Matrix Header

This record specifies that the covariance matrix (for 2DC, 2DD, 3DC, and 3DD observation sets) is to be generated. This method of generating the observation covariance matrix should only be used for simulating networks and is not meant to be a replacement for an actual covariance matrix.

The coordinate system types are:

All additive values (for entire matrix, for diagonal elements, and PPM) are applied to the matrix first, then the factors are applied. All addition constants are added directly to the covariance matrix (no squaring takes place). The PPM value is used to compute a standard deviation which is then squared before adding it to the diagonal elements of the covariance matrix.

**The format of this record is as follows (from column - to column: description):**- 002-005: GENC
- 007-008: Coordinate system of covariance matrix (LG or CT)
- 010-013: Matrix form (UPPR or DIAG)
- 015-024: Addition constant for entire covariance matrix
- 026-035: Scale factor for entire covariance matrix
- 037-046: Addition constant for diagonal of covariance matrix
- 048-057: Scale factor for diagonal of covariance matrix
- 059-068: PPM addition for diagonal of covariance matrix
- 070-079: Addition constant for height/Z
- 081-090: Scale for height/Z
- 092-093: Linear unit name

The coordinate system types are:

- LG: Local geodetic (North, East, Up)
- CT: Conventional Terrestrial (Geocentric X, Y, Z)

All additive values (for entire matrix, for diagonal elements, and PPM) are applied to the matrix first, then the factors are applied. All addition constants are added directly to the covariance matrix (no squaring takes place). The PPM value is used to compute a standard deviation which is then squared before adding it to the diagonal elements of the covariance matrix.