To me, if u allow someone to reserve an item without a deposit, then u are just asking for it.
Look at it from a buyers perspective, it makes sense for me to register my interest by reserving an item, but there is no impetus for me to go through with the purchase cause i have not paid a deposit for it. From a sellers perspective, if u allow someone to reserve, then u are restricting yourself to not being able to sell it to someone else.
Its not a question of terminology and whether other members abide by it - even if CS were to come up with a code of conduct for members, there is still no way for the code to be policed and punishment meted out to people who break the code.
Bottom line, potential buyers can agree to anything, but they have no obligation to carry it out should they decide not to buy. If u wanna B&S, then learn to be a smart seller fast.