true
if the HTMLElement is included in the Tab; false
if it is excluded.
data-caption='foo'
data-constant='true' data-constant='false'
data-dropdown-header-label='foo'
data-enable-duplicate-filtering='true' data-enable-duplicate-filtering='false'
data-enable-responsive-mode='true' data-enable-responsive-mode='false'
data-expression='foo'
data-icon='foo'
data-id='foo'
data-maximum-age='10'
data-pipeline='foo'
data-sort='foo'