ZMS 1.0 section 3.3 says:
In Versions 3 and later, Z-characters 1, 2 and 3 represent abbreviations, sometimes also called 'synonyms' (for traditional reasons): the next Z-character indicates which abbreviation string to print. If z is the first Z-character (1, 2 or 3) and x the subsequent one, then the interpreter must look up entry 32(z-1)+x in the abbreviations table and print the string at that word address. In Version 2, Z-character 1 has this effect (but 2 and 3 do not, so there are only 32 abbreviations).
I am assuming that this is the defined behavior when alphabet A0 is selected. Is there a definition of what happens if the alphabet has been shifted to A1 or A2?
Also, since only 64 abbreviations are allowed by Inform 6, would a 3 code here mean that the selected range was illegal?