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

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To retrieve a relationship, the dictionary can be open in read, read only, shared update, or exclusive
update mode. You retrieve a relationship to determine whether it exists, or to retrieve one or more of its
attribute values. You can request a value for any attribute associated with the relationship type, or for any
alias or variable-length attribute.
When the dictionary is open in read, read only, shared update, or exclusive update mode, System
Dictionary allows you to retrieve dictionary structure information that is needed to create, delete, modify,
and retrieve relationships. You can retrieve a list of relationship types and relationship classes available
in the dictionary. Also, you can retrieve the list of attributes associated with a relationship type, and a list
of the alias and variable-length attributes since you can assign these to any relationship.
Detailed instructions for creating, deleting, modifying, and retrieving relationships are located in other HP
System Dictionary/XL manuals. Refer to the HP System Dictionary/XL SDMAIN Reference Manual
(32256-90001) for instructions to do these operations with the System Dictionary user interface, or to the
HP System Dictionary/XL Intrinsics Reference Manual (32256-90002), if using the System Dictionary
intrinsics.
Entity Types
An entity type is a template for defining entities in the dictionary. System Dictionary comes with a set of
built-in entity types, called core set entity types. The entity types of the core set are intended to be
comprehensive enough to define most subsystem objects. You can also add new entity types if desired. In
System Dictionary, the ability to add new entity types is restricted to users with a special capability (the
extend scope-right).
An entity type has two parts:
• The entity type name.
• A list of attributes associated with the entity type.
You can think of entity types as categories. All IMAGE data base entities, for example, are grouped under
the entity type IMAGE-DATABASE. You can also view an entity type as a qualifier. If a VPLUS form and
an IMAGE data set both happen to be named CUSTOMERS, you can define the form as an entity of type
FORM, and the data set as an entity of type IMAGE-DATASET. Since it is possible to have multiple
entities with the same name, you must qualify an entity by specifying its entity type.
You cannot delete one of the entity types involved with the relationship type unless you explicitly request
that all the relationship types involving that entity type are to be deleted.
Specifying Attribute Lists
Entity types have attribute lists such that each entity of the type must have a value for each entity in the
list. Every entity type has built-in attributes, called special attributes (special attributes are discussed
later in this chapter). When you create an entity type, System Dictionary automatically associates these
attributes with the new entity type.
In addition, each entity type may have other attributes associated with it. For each attribute in an entity
type’s attribute list, there must be a corresponding attribute value assigned to each entity of that type. You
can add attributes to an entity type’s attribute list by creating type-attribute associations (discussed later).
Creating and Accessing Entity Types
You can create, delete, modify, and retrieve entity types. The actual instructions for doing these operations
are located in other HP System Dictionary/XL manuals. Refer to the HP System Dictionary/XL SDMAIN