SPACI score report for 3c6g in ASTRAL 2.01:

PDB Entry: 3c6g
SPACI score: 0.3
AEROSPACI score: 0.3

Experiment type: XRAY
Resolution: 2.8
R-factor: 0.195
PCK1 PROCHECK Ramachandran: 1
PCK2 PROCHECK Chi-1 angle: 1
PCK3 PROCHECK H-bonds: 2
WCK1 WHAT_CHECK Packing: -0.937
WCK2 WHAT_CHECK Ramachandran: -1.977
WCK3 WHAT_CHECK Chi angles: -0.946
WCK4 WHAT_CHECK Backbone: -0.138

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).