Labels in the widget

The widget exposes atom labels two ways: the dynamic atom-labels attribute, and the atomLabels group inside the JSON options attribute (which is passed unchanged to the internal CrystalViewer, so everything from Activating labels applies).

The atom-labels attribute

<cifview-widget
    src="structure.cif"
    atom-labels='["C1", {"id":"O1", "text":"O(carbonyl)", "priority":10}]'>
</cifview-widget>

The shorthand values all, non-hydrogen, and none are also accepted. Plain selectors match every displayed symmetry copy; use a qualified ID such as C1|2_555 to select one copy. Because it is an observed attribute, changing it later (e.g. from your own JavaScript) re-labels the structure without reloading.

Placement and appearance via options

Placement mode and appearance use the same camelCase paths as the library:

<cifview-widget
    src="structure.cif"
    atom-labels="non-hydrogen"
    options='{"atomLabels":{"placementMode":"maximum-coverage","calloutPlacement":"viewport"}}'>
</cifview-widget>

See How placement works for what the modes do, and Options Reference → Atom labels for all options.