SPACI score report for 3g18 in ASTRAL 2.07:

PDB Entry: 3g18
SPACI score: 0.54
AEROSPACI score: 0.54

Experiment type: XRAY
Resolution: 1.6
R-factor: 0.227
PCK1 PROCHECK Ramachandran: 1
PCK2 PROCHECK Chi-1 angle: 1
PCK3 PROCHECK H-bonds: 2
WCK1 WHAT_CHECK Packing: -1.264
WCK2 WHAT_CHECK Ramachandran: -1.333
WCK3 WHAT_CHECK Chi angles: -0.323
WCK4 WHAT_CHECK Backbone: -0.946

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).