Elementary conditions - find referenced Feature

A child or descendant element of an AIXM feature/object has an xlink:href attribute that has a value representing a reference to another feature. The target feature exists in the data set that is being verified.

Note: this elementary condition does not exclude the possibility that several target features exist in the data set. If a  first one is retrieved, then the condition is True. Multiple target situations are dealt with by different rules, which verify the uniqueness of UUID value and the non-duplication of the data.

This condition applies the feature referencing possibilities defined in the AIXM Feature Identification and Reference specification:

• abstract reference (by UUID, see chapter 3.4). This is the most common situation.
• concrete local reference (by gml:id, see chapter 3.2). This is also relatively common, but it works only when the referenced feature is in the same AIXM file.
• concrete external reference (by URL, see chapter 3.3). This is only a theoretical possibility, not used by any known system.