Usage:
label [ offset default | x,y,z ] atom-spec

Usage:
~label atom-spec

Label displays labels for all atoms in atom-spec. The default label information is atom name with any alternate location ID appended, but can be changed with labelopt info to element, atom type, or another atom attribute, or even to residue information (note rlabel shows residue labels, as opposed to atom labels with residue information). ~Label removes atom labels.

Label font and size can be set in the Background preferences.

By default, the offset of a label is automatically adjusted based on the display style of the corresponding atom. The offset keyword allows specifying an absolute offset that will not be adjusted, or a return to the default behavior. The word default can be truncated. An absolute offset is specified by three comma-separated values x,y,z representing distances along the X-, Y-, and Z-axes in the laboratory coordinate system:

• the X-axis is horizontal in the plane of the screen, increasing to the right
• the Y-axis is vertical in the plane of the screen, increasing upward
• the Z-axis is perpendicular to the screen, increasing outward (toward the viewer)

Various labeling tasks require approaches other than label:

• to label an atom with arbitrary text, select the atom and either choose Actions... Label... other... and enter the desired text, or open the Selection Inspector and enter the desired text in the label field
• to label a bond or pseudobond, select it and use the Selection Inspector to create or change its label
• to show temporary "balloon" labels, useful for quick identification of an atom or bond: set Show atomspec balloon in the General preferences to true (default) and place the cursor over the atom or bond of interest. The label information will appear and remain until the cursor is moved away.
• to create arbitrary labels independent of any displayed items, use 2dlabels