Many years ago, when I was serving in the army full-time, we had to be in camp from Monday to Saturday morning, and then we would book out of camp on Saturday afternoons. Sometimes we might get a Saturday off for good performance, but we cannot disappear without an offpass. The offpass was necessary to prove that one was not in camp for a valid reason, and with approval. The details in the offpass include our name, unit, and the reason for not being in camp. Before it could take effect, it had to be signed by the approving officer. And for Saturday off, we would write LWE under the “reason” section.
LWE = long weekend