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

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operations 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.
Relationship Classes
A relationship class is a name in the dictionary structure that you can use to express the action or
connection of a relationship type. See the Syntax discussion in Chapter 2 for more information on
relationship class names. The System Dictionary core set contains several commonly used relationship
classes. You can add relationship classes to the dictionary, and you can change external names of the core
set classes.
In System Dictionary, relationship types belong to a relationship class. For example, it is possible to
retrieve all the relationship types that belong to a relationship class. To get a list of all the relationship
types in the dictionary, you must first get the list of relationship classes and retrieve the relationship types
of each class.
You can create, delete,modify, and retrieve a relationship class. The actual instructions for doing these
operations 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.
You cannot delete a relationship class without explicitly requesting the deletion of all the relationship
types of that class.
Attributes
An attribute is a characteristic, property, or description of an entity or relationship. In System Dictionary,
attributes are dictionary structures that allow attribute values to be assigned to entities and relationships.
System Dictionary has a core set of attributes that are built into every dictionary. You can also create an
extended set of attributes if desired.
An attribute definition has four parts:
• The attribute name.
• The attribute type (alias, Boolean, character, floating, integer, or variable).
• The attribute length--a value, dependent on the attribute type, that specifies the maximum length al-
lowed for values of the attribute.
• An optional list of edits that specify the default and allowable values for attributes of type Boolean, char-
acter, floating, and integer.
You can associate attributes of type Boolean, character, floating, or integer with an entity type or
relationship type. Attributes of type alias and variable are "free-floating" in that they are never associated
with an entity type or relationship type but you can assign them to any entity or relationship. In either
case, attributes serve as templates for defining the attribute values of entities and relationships. Attribute
values do not exist independently. They are always associated with a specific entity or relationship. When
you delete an entity-type-attribute association, System Dictionary must remove the corresponding
attribute value from each entity of the affected type.
Since attributes are part of the dictionary structure and are available to you, you should avoid obscure or