hidden/invisible ref?

Question

I am writing a textbook which I want to be consistent. Sometimes I do not refer to a statement explicitly, but I want to add an invisible reference, so if latter I will decide to delete the corresponding statement I will see a LaTeX error.

Is there a simple or/and standard way to do it?

Answer 1

you could use

 \newcommand\hiddenref[1]{\sbox0{\ref{#1}}}

which makes \hiddenref{xx} typeset the reference into a box that is then not used.