While trying to answer an etymological question, I was looking through several different online resources about Etruscan vocabulary. Annoyingly, although these resources use mostly the same transcription system, there are a few significant differences.
Specifically, some sources use «th ph kh» for , while others use Greek «θ φ χ» (sometimes substituting Latin «þ» and «x»). And some seem to mix the two styles: Wikipedia "Etruscan language" mentions both zilaχ and zilath as words for "praetor".
When a source uses both digraphs and Greek letters for the Etruscan aspirates, is there a reason for this? For instance, do inscriptions distinguish between «θ» and «th»? (If so, are there theories on what the distinction could mean phonologically?) Or is it just inconsistent editorial preference, like macrons on Latin vowels?
