The origin, AS-path, and next hop Border Gateway Protocol (BGP) attributes are best described as well-known, mandatory BGP path attributes.

Support for optional BGP path attributes is not required of any BGP implementation. However, optional attributes must still be handled by BGP in either a transitive or nontransitive fashion.
Optional, transitive path attributes are passed to BGP peers regardless of whether support for the attribute is available. Aggregator and community are both optional, transitive BGP attributes. Optional, nontransitive BGP attributes are silently discarded if support for the attribute is not available.
Cluster list, originator ID, and multi-exit discriminator (MED) are optional, nontransitive BGP attributes.
Well-known BGP attributes are required path attributes that must be supported by every BGP implementation. Well-known, mandatory attributes must be sent in every BGP update message. Well-known, discretionary attributes, on the other hand, are only included in BGP update messages under specific sets of circumstances. Atomic aggregate and local preference are both well-known, discretionary BGP attributes.