Table 2.

Data validation with current system

Class	What is checked
Stereochemistry	Bond distances and angles, dihedral angles (Ramachandran plot), planarity of groups, chirality
Bonded/non-bonded interactions	Crystal packing, unspecified inter- and intra-residue links
Crystallographic information	Matthews coefficient, Z-value, cell transformation matrices
Noncrystallographic transformations	Validity of noncrystallographic symmetry
Primary sequence data	Discrepancies with sequence databases
Secondary structure	Generated automatically or visually checked
Heterogen groups	Geometry and nomenclature
Miscellaneous checks	Solvent molecules outside the hydration sphere, syntax checks, internal data consistency checks