This CSS attribute can be used to specify the label used for an opening custom tag (e.g. <CustomTag>). This attribute should not be used with an empty tag. The label for empty tags can be specified through the ephox-label attribute.

The following example specifies the label Custom Tag for the start tag label and /Custom Tag for the end tag label of the custom tag MyTag.

MyTag{
  display: block;
  ephox-start-label: Custom Tag;
  ephox-end-label: /Custom Tag;
}