RCW 10.64.060: Form of sentence to penitentiary.

In every case where imprisonment in the penitentiary is awarded against any convict, the form of the sentence shall be, that he or she be punished by confinement at hard labor; and he or she may also be sentenced to solitary imprisonment for such term as the court shall direct, not exceeding twenty days at any one time; and in the execution of such punishment the solitary shall precede the punishment by hard labor, unless the court shall otherwise order.