resno fields within a pdb file

Question

[rayoub]

Are the resno fields within the ATOM records of PDB files within a single chain always consecutive? I understand insertion codes may be present. Aside from that, are they always consecutive regardless of what index they start at?

Answer 1

[Petr Ponomarenko]

I do not know of such a rule in pdb file format specification ftp://ftp.wwpdb.org/pub/pdb/doc/format_descriptions/Format_v33_A4.pdf . Information about some atoms or residues can be missing and if so there is a section in remarks describing what exactly is missing with some comments like why it is missing and so on. I do not remember very well.