For answering questions like "where are we?" or "how to go there?" we need geoinformation. Geoinformation is also used for making maps. Geoinformations' characteristic is its combination of geometry (position, size ...) and thematic information (e.g. building, forest etc.).

The analytic way to describe geometry of geoinformation is the coordinate-method. The coordinate systems used for geoinformation are called coordinate reference systems (CRS). Different tasks often also use different CRS: e.g. in construction engineering, national map making, cadastral, statistics, presentations... .

For many tasks, you need geoinormation from different sources. Often, they are hold in different coordinate reference systems. To use these different datasets together, you need to unify the coordinate reference system. Read e.g. [Voser 1996 ]-

For combined usage, geodatasets need to be in the same coordinate reference system

For the hamonization of coordinate refernece systems, you need various information and utilities.

Even nowadays (2017) it is difficult to find information about coordinate reference systems even though there exist offical collections or many geospatial applications support offical CRS by using databases with parameters for change.

MapRef was built up in 1996 by the author due to user requirement and his experiense in corresponding projects for unifiying European datasets and developping GIS solutions for georeferencing for governements. MapRef is designed as a collection of authoritative coordinate reference sytems, with the main focus Europe, namely geodetic reference systems, map projections as far as freely available. The author was and still is one of the few experts in this topics. His works also are well used in education.