Initial [p] in Danian was aspirated to [pʰ] and so develop into [f] when aspirates became voiceless spirants (PE19/18, 22). Tolkien noted that this change was peculiar to Danian (PE19/22). The same change took place in the Germanic languages that inspired Danian as part of Grimm’s Law, but in Germanic the change occurred for all voiceless stops, not just [p] (ref/@@@). In Tolkien’s original notes, he said this change also applied to Ilkorin, but according to Christopher Gilson, this is almost certainly a reference that Tolkien forgot to delete when he changed Ilkorin from a Germanic-type to a Welsh-type language (PE19/22 note #54, 55)