AutoCAD® 2002 - Autodesk

NOTE If you use 1005 xdata group codes to store handles, they are treated as
soft-pointer handles, which means that when groups of objects are copied or
inserted into another drawing, references between the involved objects are
translated. Although 1005 xdata items are always returned as handles in
AutoLISP and ObjectARX, all of the reference handle group code ranges are
represented as “entity names” in AutoLISP and as ads_name structures in
ObjectARX.
Pointer and Ownership References
A pointer is a reference that indicates usage but not possession or responsibility
for another object. Pointer references mean that the object uses the
other object in some way, and shares access to it.
An ownership reference means that an owner object is responsible for the
objects for which it has an owner handle. Ownership references direct the
writing of the entire DWG and DXF files in a generic manner, such as beginning
from a few key root objects.
An object can have any number of pointer references associated with it, but
it can have only one owner.
Hard and Soft References
Hard references, whether they are pointer or owner, protect an object from
being purged. Soft references do not.
In AutoCAD, block definitions and complex entities are hard owners of their
elements. A symbol table and dictionaries are soft owners of their elements.
Polyline entities are hard owners of their vertex and seqend entities. Insert
entities are hard owners of their attrib and seqend entities.
When establishing a reference to another object, it is recommended that you
think about whether the reference should protect an object from the PURGE
command.
Arbitrary Handles
Arbitrary handles are distinct in that they are not translated to session persistent
identifiers internally, to entity names in AutoLISP, and so on. They are
stored as handles. When translation of handle values are translated in drawing-merge
operations, arbitrary handles are ignored.
Persistent Inter-Object Reference Handles | 167