For general linguistics, the Combining half marks are not recommended for usage. Instead, U+0360  COMBINING DOUBLE TILDE and U+0361  COMBINING DOUBLE INVERTED BREVE are the preferred characters to use.

Thus, to put the U+0361 COMBINING DOUBLE INVERTED BREVE over an “ia”, the preferred encoding would be to put the U+0361 between “ia” (i + U+0361 + a):



However, there are four diacritics that can produce a similar display. These are used within the Latin-script in the library world: U+FE20..U+FE23.

U+FE20 COMBINING LIGATURE LEFT HALF
U+FE21 COMBINING LIGATURE RIGHT HALF
U+FE22 COMBINING DOUBLE TILDE LEFT HALF
U+FE23 COMBINING DOUBLE TILDE RIGHT HALF

Transliterated Cyrillic records also make heavy use of the first two.

An example of how they can be used is below. Positioning of these may not be perfect.