P - empty point POINT EMPTY 1.7976931348623157E308 LINESTRING EMPTY P - single point POINT (100 100) 1.7976931348623157E308 LINESTRING EMPTY mP - points MULTIPOINT ( (100 100), (10 100) ) 90 LINESTRING (100 100, 10 100) mP - two identical points MULTIPOINT ( (100 100), (100 100) ) 1.7976931348623157E308 LINESTRING EMPTY mP - points MULTIPOINT ((100 100), (10 100), (30 100)) 20 LINESTRING (10 100, 30 100) L - linestring LINESTRING (100 100, 200 100, 200 200, 150 150) 50 LINESTRING (150 150, 150 100) L - empty linestring LINESTRING EMPTY 1.7976931348623157E308 LINESTRING EMPTY ML - linestring MULTILINESTRING ((100 100, 200 100, 200 200, 150 150), (100 200, 150 170)) 14.142135623730951 LINESTRING (150 170, 160 160) A - empty polygon POLYGON EMPTY 1.7976931348623157E308 LINESTRING EMPTY A - single polygon #1 POLYGON ((100 100, 300 100, 200 200, 100 100)) 100 LINESTRING (200 200, 200 100) A - single polygon #2 POLYGON ((300 400, 100 350, 250 320, 50 250, 298 200, 50 150, 150 100, 300 50, 300 50, 300 50, 300 400)) 2 LINESTRING (298 200, 300 200) mA - multiple polygons MULTIPOLYGON (((100 100, 300 100, 200 200, 100 100)), ((150 250, 250 250, 200 220, 150 250))) 20 LINESTRING (200 200, 200 220)