Determine if an srid refers to a geodetic CRS

Hi,

I'm wondering if there is an easy way to detect if an srid refers to a
geodetic CRS, by checking the spatial_ref_sys table.

1) Would it be safe to assume the srid is a geodetic CRS if the value in
the srtext column starts with 'GEO'? It almost seems to be too good to be
true...

2) Did I overlook a Postgis function that returns this information (and if
so, which one would that be)?

Thanks in advance,

Kind regards
Richard.