These functions require access to mimetype settings inside MarkLogic configuration, which is probably the reason why they are unavailable. To get something similar to format based on a node or document at hand, use xdmp:node-kind
instead. Content-type will need to be calculated upfront unfortunately, during ingest.
HTH!
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…