Last modified: 2014-07-12 23:17:04 UTC
For each letter in the original title, {{DISPLAYTITLE}} should allow all the letters based on the same ASCII character, but with different diacritics. For instance, instead of s, the DISPLAYTITLE should allow ś, Ś, Ŝ, ŝ, Ş, ş, Š, š, Ṡ, ṡ, Ṣ, ṣ, Ṥ, ṥ, Ṧ, ṧ, Ṩ, ṩ.
I don't think this is a good idea. One reason for restricting DISPLAYTITLE is so that the title can be copied and used in links. Such links will lead to the wrong page if the displayed title has different diacritics than the pagename. Also diacritics are allowed in pagenames, so if the title should display with other diacritics it can be moved to a pagename with the correct diacritics.
WONTFIX per Lejonel.