HP System Dictionary/XL General Reference Manual Vol 1 (32256-90004)

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4 Domains and Versions
Overview
This chapter provides a description of domains and versions, which are the spaces within System
Dictionary where the entities and relationships reside. Information on security for domains and versions
is discussed in Chapter 5 of this manual.
Domains and Versions
One important function of a data dictionary is to maintain standardization of the data in an information
system. As shown in the previous chapter, System Dictionary includes this capability by providing you
with a standard set of structure definitions, but also the means to extend them to meet your particular
needs.
Similarly, System Dictionary provides you with the means for maintaining a standard set of occurrences--
the entities and relationships. However, though most of the occurrences in a data dictionary are meant to
be shared by all users, there are sometimes circumstances, applications, or users that need separate sets of
occurrences.
System Dictionary handles these needs by allowing multiple spaces called domains within a single
dictionary. Domains are similar in some ways to accounts in the MPE file system, and you can use them as
separate partitions for different applications, or as "name spaces" to separate duplicate names used for
different purposes.
Figure 4-1 shows examples of domains that could exist within a particular configuration of System
Dictionary. The center area represents the common domain, which is the domain provided with System
Dictionary. The other spaces represent user-created domains, called local domains. The common domain
and local domains are discussed further on in this chapter.
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Figure 4-1. Dictionary Domains
Using Domains
You can use domains to satisfy a number of your needs. Some of the more common uses for domains are:
• Providing partitions for separate applications, or "name spaces" for different definitions which have the
same name.
• Providing spaces for temporary definitions which may be deleted all at once by simply deleting the do-
main that contains them. This is similar to storing files in a temporary account in MPE and then delet-
ing the account. Note that you can also do this at the version level, just as you can create a temporary
group within an account and then purge when you no longer need it. Versions are discussed further on
in this chapter.
Using Domains as Name Spaces
You can use domains as "name spaces" to avoid naming conflicts that can occur when two or more of you
want to use the same name for different purposes. For example, the Personnel and Manufacturing