Representing second derivatives with a double overdot

Question

I would like to express a second derivative with two dots above the variable. You can do this with a first derivative by saying:

f[x_] := OverDot[x];
Print[HoldForm[f[x]], " == ", f[x]]

Is there a possible syntax to do this with the second derivative?

Answer 1

g[x_] := Overscript[x, ".."]
Print[HoldForm[g[x]], " == ", g[x]]

You could use AdjustmentBox to tweak the two dots, but maybe this is not necessary.

Answer 2

You may also find utility in this:

Format[f''[x_]] := Overscript[x, ".."]

f''[j]

See the documentation for Format for more information.