U+0308 "̈" Combining Diaeresis Unicode Character

U+0308 "̈" Combining Diaeresis is a diacritical mark that is placed above a base character to indicate that the vowel should be pronounced separately from the preceding vowel, a function known as diaeresis, or to signal a change in sound, such as in umlaut. It is a combining character, meaning it does not stand alone but is applied to a preceding letter, as seen in words like "naïve" or "coöperate" in English, or in German "ü". This mark differs from the similar-looking umlaut primarily in linguistic context, though they share the same Unicode code point.