Owners can be either hard or soft owners of their objects.
Hard Ownership
The following are three examples of hard ownership:
- A database object is a hard owner of its extension dictionary.
- The block table is a hard owner of the model space and paper space block table records (but not the other block table records).
- Extension dictionaries are hard owners of their elements.
Soft Ownership
A soft ownership ID (of type AcDbSoftOwnershipId) does not protect the owned object from purge. The following are examples of soft ownership:
- In most cases, symbol tables are soft owners of their elements (exceptions include the block *MODEL_SPACE, *PAPER_SPACE, *PAPER_SPACE0, and layer 0; for these elements, the symbol table maintains a hard reference).
- Dictionaries are soft owners of their entries (but you can flag a dictionary to be a hard owner of its entries).