SPACI score report for 18gs in ASTRAL 2.08:

PDB Entry: 18gs
SPACI score: 0.47
AEROSPACI score: 0.47

Experiment type: XRAY
Resolution: 1.9
R-factor: 0.181
PCK1 PROCHECK Ramachandran: 1
PCK2 PROCHECK Chi-1 angle: 2
PCK3 PROCHECK H-bonds: 2
WCK1 WHAT_CHECK Packing: -1.218
WCK2 WHAT_CHECK Ramachandran: -0.835
WCK3 WHAT_CHECK Chi angles: -1.501
WCK4 WHAT_CHECK Backbone: -0.983

Note: Here are links to pages about PROCHECK and WHAT_CHECK.

Here is the full WHAT_CHECK report on this protein (linked from the WHAT_CHECK site).