For human-readable Map format description, see the GPXSee documentation page, for XML validation use the XSD file1.
1. Two XSDs exist for the 1.0 file format. They are content-identical and
differ only in the xmlns URI. This file refers the obsolete
http://www.gpxsee.org/map/1
xmlns. Use the replacing
http://www.gpxsee.org/map/1.0
xmlns with the corresponding
XSD wherever possible.