The original way to denote an umlaut in German was to write a small e on top of the umlauted letter, like in the second row of the image below. Is this form of the umlaut availabe via Unicode? In LaTeX, you can use the package
yfonts and then the command
\* to get such an umlaut, but I am not sure whether there is a regular codepoint for letters umlauted this way.
I think, this is a bit offtopic, but since I don't know where to post this, I post it here because I find tex.SE the place where the people are most likely to answer this question.