When I open PDB model 4hhb.pdb in PyMol:

PyMOL>load d:\pdbs\4hhb.pdb
HEADER    OXYGEN TRANSPORT                        07-MAR-84   4HHB      4HHB   3
COMPND    HEMOGLOBIN (DEOXY)                                            4HHB   4
 ObjectMolecule: Read secondary structure assignments.
 ObjectMolecule: Read crystal symmetry information.
 Symmetry: Found 2 symmetry operators.
 ObjectMolReadPDBStr: using SCALEn to compute orthogonal coordinates.
 CmdLoad: "d:\pdbs\4hhb.pdb" loaded as "4hhb".

it says: "using SCALEn to compute orthogonal coordinates."
So why orthogonal coordinates are re-computed for 4hhb.pdb ?
Besides, in PDB format document it says:

The SCALEn (n = 1, 2, or 3) records present the transformation from the orthogonal coordinates as contained in the entry to fractional crystallographic coordinates.

It seems using SCALEn and coordinates presented in PDB file one should get fractional coordinates in the end.

I am using pymol version 0.99rc6 and my OS is window XP SP2.

Thanks for your answer!
Wolfgang Meyer