Hfrhyu

I wanted to make a notation with a double dot over a symbol in Mathematica. Searching online or in the documentation did not yield any results. However, just randomly attempting to give a second parameter to the OverDot function surprisingly did exactly what I needed:

I assume the red font suggests that Mathematica perceives this as a syntax mistake at some level, even though the output is as desired. Unfortunately, this does not work for three dots and more.

Is there a proper way to do this without red font appearing?

Use ToBoxes to find the boxes generated for OverDot[x, 2]:

OverDot[x,2] //ToBoxes

OverscriptBox["x", "¨"]

You can reproduce these boxes using Overscript:

Overscript[x, RawBoxes @ "¨"]

You can use the same approach for triple dots:

Overscript[x, RawBoxes @ "[TripleDot]"]

For more dots, you will have to use a different mechanism to generate the dots, e.g.:

Overscript[x, Style[Row[".",".",".","."],FontTracking->"Condensed"]]

Update

You could also overload OverDot to work with the 3 and higher versions (I also included @Michael's syntax information fix):

SyntaxInformation[OverDot] = "ArgumentsPattern" -> _, _.;
MakeBoxes[OverDot[a_, n_Integer?(GreaterThan[2])], StandardForm] := If[n==3,
 OverscriptBox[MakeBoxes[a], "[TripleDot]"],
 OverscriptBox[
 MakeBoxes[a],
 ToBoxes @ Style[Row[ConstantArray[".", n]], FontTracking->"Condensed"]
 ]
]

Then:

You could fix the syntax highlighting, or ignore it. Here's a fix:

SyntaxInformation[OverDot] = "ArgumentsPattern" -> _, _.;

Go to the Basic math assistant palette and click on the template.