An ONIX code indicating the level of the collection title element (collection level or sub-collection level) to which the identifier in the <IDValue> element is assigned. Optional in each occurrence of the <CollectionIdentifier> composite, and non-repeating.

When used, the specified level must match the level of a <TitleElement> within the same Collection composite, or – is there is no <TitleDetail> within the Collection composite – the level of a <TitleElement> within Group P.6.