An expression is “embodied in” a manifestation; conversely, a manifestation is the embodiment of an expression. In this case the logical connection serves as the basis both for identifying the expression of a work embodied in an individual manifestation and for ensuring that all manifestations of the same expression are linked back to that expression. Indirectly the relationships between an expression and the various manifestations of that expression also serve to establish an implicit “sibling” relationship between the various manifestations of the expression. [Functional Requirements for Bibliographic Records: Final Report, pp.59]