When http://schema.org/ItemList was revamped, one of the use cases was a catalog. The second example is for one such use case.

As this is a common use case and seeing adoption, it would be nice to add a separate type for it:

_OfferCatalog: An OfferCatalog is an ItemList that contains Offers and/or further OfferCatalogs.
_hasOfferCatalog: Indicates an OfferCatalog listing for this Service or Organization.