Only now do I see your picture – it was taking a while to load while I made my first comment. Now I have to add this. Vienna sausages have traditionally included pork in the blend of meats used, without being called ‘pork viennas’, so I can easily see how something labelled ‘chicken vienna’ could simply mean a ‘vienna with chicken’, without having to mean ‘vienna with only chicken’, where I would still expect something labelled ‘chicken sausage’ to contain only chicken.