Okay. I see that
bt.get_Item(BlockTableRecord.ModelSpace)
or
bt.get_Item("*Model_Space")
returns an object ID, not the block table reference its self, so I have to pass that into:
t.GetObject()
This works:
with adoc.LockDocument():
with adoc.Database as db:
with db.TransactionManager.StartTransaction() as t:
bt = t.GetObject(db.BlockTableId, OpenMode.ForWrite)
btrID = bt.get_Item("*Model_Space")
btr = t.GetObject(btrID, OpenMode.ForWrite)
objectIDs = []
for oid in btr:
objectIDs.append(oid)
t.Commit()
pass
Thanks Zachri.