Reference for the Office CustomUI XML schema used to define Excel ribbon toolbars and context menus. Use this skill whenever writing, editing, reviewing, or debugging customUI XML — including ribbon tabs, groups, buttons, dropdowns, galleries, menus, context menus, the QAT, or the Backstage. Also use when working with PyXLL ribbon configuration. Training-data knowledge of the schema is incomplete and can produce invalid XML — the schema and these docs are the authoritative source.
