Information from https://www.iucr.org/resources/cif/spec/version1.1/cifsyntax

Available as MMCifEntityDesc objects in MMCifInfo

If all residues in a chain are saccharides in some form, the
respective _entity.type should be "branched"

Minimum length for a chain in the target structure
to be considered in chain mapping. The chain mapping algorithm first
performs an all vs. all pairwise sequence alignment to identify
"equal" chains within the target structure. We go for simple sequence
identity there. Short sequences can be problematic as they may
produce high sequence identity alignments by pure chance.

BUT: if you're scoring peptides or short nucleotides, you
really want to be able to reduce the default thresholds
(pep: 10, nuc: 4)

Right now there is only a static constructor for polymer entities

uint8_t got interpreted as char, it's integer now