SPACI score report for 1b6g in ASTRAL 2.08:

PDB Entry: 1b6g
SPACI score: 0.91
AEROSPACI score: 0.91

Experiment type: XRAY
Resolution: 1.15
R-factor: 0.105
PCK1 PROCHECK Ramachandran: 1
PCK2 PROCHECK Chi-1 angle: 1
PCK3 PROCHECK H-bonds: 2
WCK1 WHAT_CHECK Packing: 0.631
WCK2 WHAT_CHECK Ramachandran: -1.591
WCK3 WHAT_CHECK Chi angles: 1.578
WCK4 WHAT_CHECK Backbone: -0.801

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).