relation

An index attribute, a.k.a. relation or relational attribute, is an attribute containing as values the ordinal numbers of the elements of another domain. It thereby defines a mapping from each element of the domain for which it is an attribute to that other domain unit. The following picture illustrates this:

A relation has the source domain as domain unit and the related/target domain as values unit. It's a mapping from the source towards the elated/target domain.

Synonyms in use for relation: partitioning, relational attribute;

naming convention

It is advised to use the postfix _rel when naming index attributes, see also naming conventions.

how to make

Relations are often made with a rlookup or point_in_polygon function. See also relational attribute example.

use

Relations are often used in relational functions and aggregation functions.