There are many different classes of objects defined for the XDS interface; still more are defined by the X.500 standard for general directory use. But only a small number of classes are needed for XDS/CDS operations, and only those classes are discussed in this topic. Information about other classes can be found in Part 4 of this guide.
The class that an object belongs to determines what sort of information the object can contain. Each object class consists of a list of attributes that objects must have. For example, you would expect an object in the directory entry name class to be required to have an attribute to hold the entry name string. However, it is not sufficient to simply place a string like the following into an object descriptor:
/.../C=US/O=OSF/OU=DCE/hosts/tamburlaine/self
A full directory entry name such as the preceding one is called in XDS a distinguished name (DN), meaning that the entry name is fully qualified (distinct) from root to entry name. To properly represent the entry name in an object, you must look up the definition of the XDS distinguished name object class and build an object that has the set of attributes that the definition prescribes.