Relationship to Naming Operations

An XFN attribute operation might not be equivalently expressed as an independent fn_ctx_lookup() operation followed by an attribute operation in which the caller supplies the resulting reference and an empty name.

This is because some attribute models associate attributes with a named object in the context in which the object is named. In others, an object's attributes are stored in the object itself. XFN accommodates both these models.

Invoking an attribute operation using the target context and the terminal atomic name accesses either the attributes that are associated with the terminal name or the object named by the terminal name--this is dependent upon the underlying attribute model. This document uses the term "attributes associated with a named object" to refer to all of these cases.

XFN does not provide any guarantee about the validity of the relationship between the attributes and the reference associated with a given name. Some naming systems might store the reference bound to a name in one or more attributes associated with a name. Attribute operations might affect the information used to construct a reference.

To avoid undefined results, programmers must use the operations in the context interface and not the attribute operations when manipulating references. Applications should avoid using specific knowledge about how an XFN context implementation over a particular naming system constructs references.