This document discusses how MARC 21 fields relate to FRBR entities and RDA attributes. It provides examples of how attributes of works, expressions, and manifestations are recorded in MARC fields and explains how RDA differs from AACR2 in its conceptual model and treatment of access points. New fields are introduced in RDA to record attributes at the work, expression, and manifestation levels in a more granular way. Relationships between entities are conveyed through notes and linking fields.