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General Externalization Guidelines
The following are general externalization guidelines:
Inserting a parent into the hierarchy is handled automatically.
Removing a parent from the hierarchy requires implementation of readOldVersion for pre-Release 9.0 versions.
The old ID and fields must be read (removed) from the stream.
Changing the persistent signature of a class requires implementation of readOldVersion pre-Release 9.0 versions.
Adding or removing fields.
Changing the name or type of a field.
For Windchill Release 9.0 and beyond, the virtually all changes are handled automatically. See explanations in examples sections below for details on how the automated readVersion<EXTERNALIZATION_VERSION_UID> methods are generated.