[postgis-users] Function isvalid()

[Christina Biakowski]

Dear list,
I wonder for which criteria the function isvalid() checks geometries?
I have checked my data (MULTIPOLYGON) with isvalid() and now I am trying to
find out where the errors result from. While for a part of the geometries
for which isvalid() returned false the errors are quite obvious for me
(unclosed polygons, crossing lines without intersections/nodes) a part of
the not-valid-objects seem quite ok for me like the following example:

SRID=31492;MULTIPOLYGON(((2597146.2 5653827.98,2597156.824
5653821.184,2597160.82 5653838.11,2597164.213 5653852.142,2597173.395
5653866.878,2597257.03 5653936.45,2597253.37 5653989.33,2597248.112
5653988.184,2597244.88 5653987.48,2597248.42 5653946.81,2597245.74
5653940.22,2597167.25 5653872.7,2597160.76 5653864.92,2597156.23
5653856.5,2597154.17 5653850.63,2597146.2 5653827.98),(2597238.78
5654011.58,2597243.1 5654008.01,2597244.53 5653991.51,2597247.705
5653992.204,2597253.09 5653993.38,2597251.87 5654010.96,2597253.688
5654013.749,2597255.28 5654016.19,2597238.78 5654011.58)))

Can anybody give me a hint?

Thank you in advance,

Christina