Synonym or breeding number (also FR 25-1) for the Freisamer grape variety; see there.
The white grape variety is a new variety between Silvaner x Pinot Gris (which was confirmed by DNA analyses published in 2012). Synonyms are Freiburg 25-1 and (in Switzerland) Freiburger. The cross was made in 1926 by the vine breeder Karl Müller (1881-1955) at the State Viticulture Institute in...
Serious sources on the internet are rare - and Wine lexicon from wein.plus is one such source. When researching for my articles, I regularly consult the wein.plus encyclopaedia. There I get reliable and detailed information.
Thomas Götz
Weinberater, Weinblogger und Journalist; Schwendi