When there are records online for each title in a linking relationship, or the related title is known though no record appears online, each record should contain a link (in most cases). In some cases different tags are used for the links (e.g., 780/785); in other cases the same tag is assigned (e.g., 775).

Reciprocal Linking Relationships:

Reciprocal linking is not always possible or desirable. If one title is related to many others, a link may be made one way but not the other (e.g., many titles merge into one: a link is given on each to the later title but not on the later title to all of the previous titles). A 580 note explaining the situation is generally given instead. Though possible, reciprocal links are not made in certain cases when cataloging reproduction microforms (see CEG 776). Example:

See also:

4.1. Linking relationships and linking entry fields: an overview