Hi Hélène,
It's a custom algorithm developed by Warren DeLano. Some of the details are
discussed in this post:
https://sourceforge.net/p/pymol/mailman/message/7561993/
The implementation is in SelectorAssignSS in layer3/Selector.cpp:
Dear pymol users,
For a project based on proteins secondary structures (ss), I need to know
which algorithm/program does PyMol use to retrieve secondary structures
from a pdb file (when the ss datas are not display in the file).
I retrieved ss using dssp program, and for some pdb files, it shows
