Usually, the DAOs should be generated based on a database object XML. This way you can regenerate the DAO code to be compatible with the latest CiviCRM version.
Here, however, this XML is missing, and I think the DAOs were hand-crafted at the time, because the generating mechanism didn't work properly in extensions at that point.
bjendres
commented
2 years ago
Usually, the DAOs should be generated based on a database object XML. This way you can regenerate the DAO code to be compatible with the latest CiviCRM version.
Here, however, this XML is missing, and I think the DAOs were hand-crafted at the time, because the generating mechanism didn't work properly in extensions at that point.