Tied up (nonsexual) states,
"Physical restraint of a person in a comedic or non-sexual context, in contrast to bondage."
But to what extent is non-sexual classified on danbooru? No shibari? No ball gags? No erotic poses? No sexual/implied liquids? I believe it is necessary to discuss this to ensure the satisfaction of those seeking it.
I believe that the tagged posts should not have:
Sex toys, including ball gags.
Sexual liquids/implied sexual liquids