I was reading through the comments on a Spanish forum and it gives me the impression that Spaniards themselves do not believe that the Titulo Propio Masters are equivalent to "real" masters but rather to "certificates" or "specializations". Many comment that the title "master" does not represent the true nature of Propios and is misleading. https://www.spaniards.es/foros/trabajo/titulos-propios There are other interesting comments. Like how in some cases, a Titulo Propio can be considered like graduate credits. WES, according to one of the posters, evaluated his Titulo Propio Masters from Complutense Madrid (a top public Spanish university) as equivalent to US graduate credits.