What is the name of the function $f$, defined below?

$$f(n) = m - n\bmod m$$

or

$$n\bmod m + f(n) = m $$

If I were to make up a name, I would probably choose "complement modulus," and maybe $\mathrm{dom}$ or $\overline\bmod$ ("$\bmod$" with an overbar) for an abbreviation.

For example, the "$\bmod 4$" of the first eight natural numbers would be $(1, 2, 3, 0, 1, 2, 3, 0)$; while the "$\mathrm{dom}\ 4$" of the same would be $(3, 2, 1, 4, 3, 2, 1, 4)$.