| 7 | | July 12, 2020: **PDB 2-character chain IDs**. Column 21 in a PDB file, normally blank, is now treated as the second character of the chain ID if appropriate. Previously, non-blanks in that column were treated as the fourth character of the residue name (needed in some Amber files). Now, that column is treated as part of the chain ID as long as it is consistent across all the residues in the chain, otherwise it is treated as part of the residue name. |
| | 7 | July 12, 2020: **PDB 2-character chain IDs**. Column 21 in a PDB file, normally blank, is now treated as the second character of the chain ID if appropriate. Previously, non-blanks in that column were treated as the fourth character of the residue name (needed in some Amber files). Now, that column is treated as part of the chain ID as long as it is consistent across all the residues in the chain, otherwise it is treated as part of the residue name. This works for both input and output of PDB files. |