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

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Creating and Accessing Entities
In System Dictionary, you can create, delete, modify, and retrieve entities.
To create an entity, the dictionary must be open in shared or exclusive update mode. When you create
an entity, you must specify its external name, its entity type, an attribute list, and values for each attribute
in the list. The attribute list may contain any attribute associated with the entity type, plus any alias
attribute. Variable-length attribute values are assigned later, after you create the entity. When you create
an entity, you can specify an internal name. If you do not specify an internal name, it will default to the
external name.
Modifying an entity means changing the entity's external name or assigning new attribute values. To
modify an entity, the dictionary must be open in shared or exclusive update mode.
To delete an entity, the dictionary must be open in shared or exclusive update mode. When you delete an
entity, relationships, variable-length attribute values, aliases, and other information are also deleted. To
retrieve an entity, the dictionary must be open in read, read only, shared update, or exclusive update
mode. One reason to retrieve an entity is to determine whether it exists. Another reason is to retrieve one
or more of the entity's attribute values. You retrieve the attribute values by specifying the list of attributes
for which values are to be returned.
When the dictionary is open in read, read only, shared update,orexclusive update mode, you can retrieve
information about dictionary structure that is needed to create, modify, delete, or retrieve entities. When
you create or access an entity, you must specify the entity type. System Dictionary allows you to retrieve
the list of entity types available in the dictionary. You can also retrieve information about the attributes
associated with an entity type so that you can assign values to the appropriate attributes. Since you can
assign any alias or variable-length attribute to any entity, System Dictionary also allows you to retrieve
information about these attributes.
Detailed instructions for creating, deleting, modifying and retrieving entities are located in other HP
System Dictionary/XL manuals. Refer to the HP System Dictionary/XL SDMAIN Reference Manual for
instructions to do these operations with the System Dictionary user interface, or to the HP System
Dictionary/XL Intrinsics Reference Manual, if using the System Dictionary intrinsics.
Relationships
Relationships are dictionary definitions that express a logical connection between the real-world objects of
an information network. Most relationships involve two entities and are called binary relationships.
System Dictionary supports binary relationships, as well as N-ary relationships that involve from three to
six entities. A relationship serves two main purposes:
• Relationships express a connection between entities. The fact can be expressed that a VPLUS form
IMAGE-DATASET SCOPE-OWNER SENSITIVITY
SCOPE-CHANGED ID-NUMBER
DATE-CREATED IMAGE-DATASET-TYPE
DATE-CHANGED
Table 2: Core-Set Attribute List Examples
Entity Type Core-Set Attribute List