SPACI score report for 1si4 in ASTRAL 2.08:

PDB Entry: 1si4
SPACI score: 0.35
AEROSPACI score: 0.35

Experiment type: XRAY
Resolution: 2.2
R-factor: 0.218
PCK1 PROCHECK Ramachandran: 1
PCK2 PROCHECK Chi-1 angle: 2
PCK3 PROCHECK H-bonds: 2
WCK1 WHAT_CHECK Packing: -0.749
WCK2 WHAT_CHECK Ramachandran: -3.036
WCK3 WHAT_CHECK Chi angles: -2.496
WCK4 WHAT_CHECK Backbone: 1.051

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).