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

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A domain is part of the "access path" to System Dictionary. Therefore, you must specify a domain each

time System Dictionary is open in a mode that allows access to domains. Unlike domains that you name,

the common domain does not have a name (its name is blank), and you access it by using blanks when

specifying the domain to use.

Because only one dictionary can be open at a time through SDMAIN, you are restricted to using only one

domain at a time. You can switch to another domain (modify the current access path), but the rule that

you can use only one domain at a time is enforced. Although you can establish multiple access paths to one

or more dictionaries simultaneously via the System Dictionary intrinsics, and can switch between paths,

you can only specify one domain at a time per access path, and only one of these paths may be used at a

time. Therefore, the rule that you may use only one domain at a time is still enforced. In any case, you

must work entirely within the speciﬁed domain except when using a local domain that has links to the

common domain. (See the discussion on "linking", further on in this chapter.) Note that you are able to

access only the occurrences in the domain speciﬁed in the current access path.

Versions

Some applications require multiple versions of dictionary occurrences. System Dictionary provides a

version feature that allows multiple versions of the same entities and relationships to exist simultaneously

within a single domain. A version in the dictionary is a name space within a domain, and you can think of

it of as a partition of the domain, or as a copy of the entities and relationships in the domain.

Versions as Partitions

Versions are named partitions of a domain, and you can identify them by creating names for them. These

names must be valid System Dictionary names, and can take the form of a number such as ’051743’, or a

name such as ’TEST_VERSION_ONE’, etc. For example, a domain named MFG could contain two

versions named MFG1 and MFG2. Every domain must contain at least one version. In this sense,

versions in System Dictionary are similar to groups within an MPE account. Figure 4-2 illustrates