[Zope] accessing Python product classes from a Python script

I found the solution to the problem I posted last night about importing my product modules in a Python script: use an external method instead. [Cf. http://www.zope.org/Members/michel/ZB/ScriptingZope.dtml and search for "Import limits".] I do have a further question, though. That paragraph includes this text: "modules which have been specifically made available to scripts by product authors. See Appendix A for more information on these modules." I don't understand the reference to Appendix A -- is this a mistake? Is making a product available to scripts something anyone can do (and if so, how?), or is it just for Zope's initial products?