I’ve decided that TfL have got the name of the OEP wrong. It should actually be called the Oyster Travelcard Extension Permit (or OTEP). This would avoid the first confusion where people think it extends the oyster system so that they can travel beyond oysterisation into the home counties. It still won’t help with the understanding of the travelcard extensions, but at least people might realise that it only applies to those with a stored travelcard.