From: Charles McAnany (
Date: Wed Aug 31 2022 - 14:27:29 CDT

A colleague wanted to study the pdb 7LBM, which contains chains A-Z and
a-z. It's a ton of chains.
If I try to select "chain x" or "chain y", or "chain z", I get a "The atom
selection you entered could not be understood" error. I suspect that this
is a bug in the parser or lexer, in that the xpos, ypos, and zpos selection
syntax ("x > 10") is conflicting with the chain name selection. Putting
quotes around the chain name, (chain "x") serves as a workaround, but if
the parser can be easily modified to allow these sorts of selections, it
would be one more squashed bug and one more happy experimentalist.
I have also verified that this behavior occurs with "type x", "name x", and
"element x".
This is on vmd 1.9.3, and I also tested it on an old-ish copy of 1.9.4 I
had on my path.
Charles McAnany.