Here is a list of all documented namespace enum values with links to the namespaces they belong to:

GEOS_GEOMETRYCOLLECTION : geos::geom
GEOS_LINEARRING : geos::geom
GEOS_LINESTRING : geos::geom
GEOS_MULTILINESTRING : geos::geom
GEOS_MULTIPOINT : geos::geom
GEOS_MULTIPOLYGON : geos::geom
GEOS_POINT : geos::geom
GEOS_POLYGON : geos::geom