Can a Ballista be shot hand held?

the Roman ballista there are many forms I am talking about the one that doesn't have a clear front this giant wooden thing is blocking I think it is called the Manoballista which I know in spanish mano means hand which to my translation is correct it means Hand held Ballista I am talking about the one used on that wooden tripod where you pull back that racket thing can it be lifted and shot standing up