Variable: FACET_LABEL_NAME

const FACET_LABEL_NAME: 'facet label' = 'facet label';

name of the facet labels Express adds (day=Sat above a facet column, time=Dinner at the right of a facet row): like SUBPLOT_TITLE_NAME, those above the top row push the top margin (a top legend sits above them), but they keep layout.font's size, as px's facet labels.