This drove me nuts (did someone hit the wrong key on a typewriter?) - the original svart appeared in White Dwarf 9 and also was used in a module in the same issue. The inspiration being the svarts (from Svart-Alfar or 'Black Elves' as opposed to 'Lios Alfar' or light elves in the Alan Garner books - the Weirdstone of Brisingamen, which I read ad enjoyed as a child in the 70s), however they were transfromed into 'Xvarts' for the Fiend Folio - was it a copyright problem?