HP 3000 Manuals

HP System Dictionary XL Gen. Ref. Vol. 1

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 domain that contains them.  This is
    similar to storing files in a temporary account in MPE and then
    deleting 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 departments of a
company both want to use an entity called P-NUM. The Personnel department
defines P-NUM as a personnel number, while the manufacturing department
wants to use it for part number.  System Dictionary easily handles this
conflict by allowing you to create a domain for each application.

Within a single domain, System Dictionary does not allow two occurrences
of the same type to have the same name.  For example, you cannot have two
entities called PRODUCT-NAME of the same entity type (for example
ELEMENT) in the same domain.  The same is true for relationships of the
same relationship type.  However, System Dictionary does allow two
entities that use the same name if the entities are of different
entity-types in the same domain.  For example PRODUCT-NAME of type
RECORD, and PRODUCT-NAME of type ELEMENT do not conflict with each other.
This also applies to relationships.

Using Domains as Partitions 

Just as you can use an account in the MPE file system to contain a set of
related files, you can use a domain to contain a set of occurrences a
specific application uses.  For example, you may want to have similar
sets of occurrences for the Marketing, Personnel, Manufacturing, and R&D
departments.  You can easily accomplish this by creating a domain for
each of them, as shown in figure 4-1.  Note that this also keeps the
occurrences for that application separate from those of all others in the
dictionary.

MPE/iX 5.0 Documentation