Items in Chimera such as atoms, bonds, residues, and models have attributes: properties with names and values (details...).
The Selection Inspector provides access to attributes of items that are selected.
The Model Panel lists models of various types. Once a model has been chosen in the left side of the Model Panel, clicking the attributes... button in the right side brings up an attribute inspector:
Attributes of segmentation regions can be inspected and new attributes created using the Region Attributes dialog.
See also: setattr, defattr, vdwdefine