The term 'Key Attributes' has been superseded by the term 'Displayed Attributes' as this better reflects their purpose. For longtime users, the change occurred in v8.8.0.
All system attributes containing the string 'KeyAttributes' are deprecated in favour of new system attributes using the term 'DisplayedAttributes'.
Thus, attribute $KeyAttributes has been renamed $DisplayedAttributes. Related changes include $DisplayedAttributesFont, $DisplayedAttributesFontSize, $DisplayedAttributesDateFormat $HideDisplayedAttributes.
Existing documents may continue to refer to $KeyAttributes and will continue to operate this is so as not to break code in existing documents.
See also—notes linking to here: