Usage:
labelopt ( info | resinfo ) label-contents

Labelopt defines custom labels containing attribute values, alone or in combinations with each other and arbitrary text. For labeling with arbitrary text alone (without attribute values), setattr should be used instead. Labels already shown are not changed; if descriptor values change, the labels must be displayed again to reflect the changes. See also: label, rlabel, 2dlabels, custom residue labeling

The info keyword is used for atom labels, resinfo for residue labels. The label-contents can be:

• any single descriptor described below, primarily the name of an attribute at the appropriate level (atoms or residues), plus a few special cases
• any combination of arbitrary text and substitution codes of the form %(descriptor)format

The latter, more complicated form would be used to combine multiple descriptors with each other and with text, and/or to control specific aspects of the format such as the number of decimal places. Examples:

labelopt info B = %(bfactor).2f
label solvent
- show labels something like “B = 43.70” containing B-factor values

labelopt resinfo %(name)s %(number)s
rlabel :150-160
- show residue labels like “TYR 151”

labelopt info %(charge)+.3f
label :his
- show atomic partial charges as labels something like “-0.278” and “+0.332”

For atoms, a descriptor can be the name of any atom attribute, whether built-in or created during use of Chimera, plus a few hard-wired options that are not attributes:

• name (default) - atom name with any alternate location ID appended
• residue - model number (if multiple models are open), residue name, and residue identifier (number.chain), unless in the Labels preferences, Atomspec display style is set to command-line specifier
• molecule - model number
• element
• idatmType - atom type
• charge - partial charge such as assigned by addcharge
  (etc.)

For residues, a descriptor can be the name of any residue attribute, whether built-in or created during use of Chimera, as well as the following:

• name - residue name
• 1-letter code - one-letter residue code for standard amino acids, residue name for other residues
• specifier - residue number, insertion code, and chain ID
• number - residue number
• insertion code - residue insertion code
• chain - chain ID
• molecule - model number

For either atom or residue labels, a format can be several things, described as components #3-7 of a conversion specifier in the Python documentation, but useful possibilities include:

• s - string
• .Nf - floating-point number with N digits after the decimal point, for example .2f to give numbers like 122.57 and –1.66
• +.Nf - as above but always signed, for example +.2f to give numbers like +122.57 and –1.66