There seem to be three terms used by experts in the field However, the other two seem to be more commonly used in that context. Except non is not an english word, it is a prefix of latin origin Which is why american style manuals will always ask you to merge it with the subsequent word, without a hyphen In that context, which is more correct or more frequently used This is for writing software documentation that explains the usage of an optional property which some objects have.
You used the dash in the wrong place I might be tempted to create an open compound, but non doesn’t stand alone. For more, including variants, see wikipedia
OPEN
