[GRASS5] New Datums

[Radim Blazek]

On Wednesday 28 May 2003 16:16, Paul Kelly wrote:
> Hermannskogel seems to be in Austria so this name seemed appropriate but
> there is also S_JTSK_Ferro which applies to the Czech Republic and
> Slovakia, but are these the same datum?

I am not very sure what the 'datum' is, just from user point of view:
Acording to http://crs.ifag.de/, 'S-JTSK' is 'Datum identifier' (so it could be datum)
for Czech and Slovak Republic. 'Hermannskogel' seems to be 'Datum anchor point' 
used by more 'datums'. If datum record in datum table is something what should help
user to define transformation parameters, then we need two records for 
S-JTSK, one for Czech and second for Slovak Republic (different parameters),
S-JTSK_CZ and S-JTSK_SK?
On crs.ifag.de is distinguished only 'CRS identifier': 'CZ_S-JTSK / KROVAK'
and 'SK_S-JTSK / KROVAK'

If you use only 1 record for S-JTSK (but there are no reliable parameters 
for the whole territory available, I think), then user have to either define its own 
parameters or use wrong (not precise enough) parameters.

Radim