SPACI score report for 3u81 in ASTRAL 2.04:

PDB Entry: 3u81
SPACI score: 0.9
AEROSPACI score: 0.9

Experiment type: XRAY
Resolution: 1.13
R-factor: 0.136
PCK1 PROCHECK Ramachandran: 1
PCK2 PROCHECK Chi-1 angle: 1
PCK3 PROCHECK H-bonds: 2
WCK1 WHAT_CHECK Packing: -1.441
WCK2 WHAT_CHECK Ramachandran: -1.031
WCK3 WHAT_CHECK Chi angles: 0.451
WCK4 WHAT_CHECK Backbone: 3.24

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).