Geodetic Mark Data File Formats

Each geodetic data extract is supplied as a zip archive which can be opened with any of the standard ZIP file utilities such as WinZip, PKzip, or InfoZip.

It contains two data files for each table in the Landonline database that is extracted - a metadata file with extension ".def" that defines the data extracted, and a data file with extension ".csv".

The ".csv" file is an ASCII text file containing one record per line. The fields in each record are delimited by the pipe character "|". The first line in each file lists the names of the fields.

Detailed information about the tables that are extracted is available from the geodetic mark dataset index of tables. A simplified data model of the geodetic mark dataset tables shows how they are related to one another.

As an example, the Landonline table crs_ellipsoid defines the ellipsoids used in coordinate systems in Landonline. This is extracted into files "elp.csv" and "elp.def". The beginning of the "elp.csv" file contains:

id|name|semi_major_axis|flattening|audit_id| 1|Geodetic Reference System 1980 (GRS80) |6378137.0|298.257222101|1| 2|International Ellipsoid|6378388.0|297.0|2| 3|World Geodetic System 1972 (WGS72)|6378135.0|298.26|3|

The metadata file "elp.def" contains:

HEDR 1.0.0 SOFTWARE cbe_b30 V1.0.0 SCHEMA V1.0 USER crsprd START 2000-07-02 22:19:25 END 2000-08-06 22:23:13 SQL SELECT * FROM crs_ellipsoid TABLE crs_ellipsoid COLUMN id integer NOT NULL COLUMN name varchar NOT NULL COLUMN semi_major_axis decimal NOT NULL COLUMN flattening decimal NOT NULL COLUMN audit_id serial NOT NULL DESC

This provides some information about the structure of the table being extracted. The "END" date is the date at which the data was extracted. For incremental extracts the "START" date is the date of the previous extract - the data set contains the changes that have occurred between these dates.