The notation without slash or hash is not common. I haven't seen a vocabulary using that convention. And in the W3C recommendation they only provide recipees for slash and has URIs: http://www.w3.org/2001/sw/BestPractices/VM/http-examples/2006-01-18/#naming
Actually, if you use the one listed in your example, it may be considered slash notation, but every term in your vocabulary would start with "WishListSchema_".
From the derreferenceability point of view, the example would also lead to problems if you use purl, as you would have to create a different purl for each concept of your vocabulary. Instead, if you use something like http://purl.org/net/WishListSchemwish# you could redirect the URL to you server and use the appropriate recipee for publising the vocabulary.
Thank you, it is true the variety with hash makes sense because if used, the link directs me to downloading of the schema (ttl). Anyway, is it common or “allowed” to use such a small vocabulary/schema in a shape of an rdf/ttl/json or so file?
I don't know if I undestood your question correctly. You can store your vocabularies as you wish. And rdf/ttl is common (I often save them in owl or ttl). But if you want to document your vocabulary (like create an html file), you can enable content negotiation and let the user download either html or your file (which may be on ttl). You just have to follow the w3C link I posted for more info