HP Integrity NonStop J-Series - Manual (Page 211)

Define All RWCollectables That Will Be Restored
Make certain that your program declares variables of all possible RWCollectable objects that you
might restore. For an example of this practice, see example 2 , above.
These declarations are of particular concern when you save an RWCollectable in a collection,
then attempt to take advantage of polymorphic persistence by restoring the collection in a
different program, without using the RWCollectable that you saved. If you don't declare the
appropriate variables, during the restore attempt the
RWFactory will throw an RW_NOCREATE
exception for some RWCollectable class ID that you know exists. The RWFactory won't throw
an RW_NOCREATE exception when you declare variables of all the RWCollectables that could
be polymorphically restored.
The problem occurs because your compiler's linker only links the code that RWFactory needs to
create the missing RWCollectable when that RWCollectable is specifically mentioned in your
code. Declaring the missing RWCollectables gives the linker the information it needs to link the
appropriate code needed by RWFactory.