### 3.7.130. Joker value

Denotes that, for some variables of a given constraint, there exists specific values that have a special meaning: for instance they can be assigned without breaking the constraint. As an example consider the $\mathrm{𝚊𝚕𝚕𝚍𝚒𝚏𝚏𝚎𝚛𝚎𝚗𝚝}_\mathrm{𝚎𝚡𝚌𝚎𝚙𝚝}_\mathtt{0}$ constraint, which forces a set of variables to take distinct values, except those variables that are assigned to 0.