SPACI score report for 3us6 in ASTRAL 2.04:

PDB Entry: 3us6
SPACI score: 0.7
AEROSPACI score: 0.7

Experiment type: XRAY
Resolution: 1.45
R-factor: 0.168
PCK1 PROCHECK Ramachandran: 1
PCK2 PROCHECK Chi-1 angle: 1
PCK3 PROCHECK H-bonds: 1
WCK1 WHAT_CHECK Packing: 0.693
WCK2 WHAT_CHECK Ramachandran: -0.754
WCK3 WHAT_CHECK Chi angles: 0.641
WCK4 WHAT_CHECK Backbone: 6.13

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).