SPACI score report for 1t20 in ASTRAL 2.06:

PDB Entry: 1t20
SPACI score: 0.41
AEROSPACI score: 0.41

Experiment type: XRAY
Resolution: 2.2
R-factor: 0.197
PCK1 PROCHECK Ramachandran: 1
PCK2 PROCHECK Chi-1 angle: 1
PCK3 PROCHECK H-bonds: 2
WCK1 WHAT_CHECK Packing: -0.476
WCK2 WHAT_CHECK Ramachandran: -0.022
WCK3 WHAT_CHECK Chi angles: -0.168
WCK4 WHAT_CHECK Backbone: 1.155

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).