A cube has 6 sides. To be enclosed all six have to be present. Very simple definition and that is how you enclose a space. You can 'enclose' a yard with fencing on the perimeter in 2 dimensions, but we are talking 3 dimensions here. Under King in the COA this is a moot point, there has to be a top and that has been settled. And for that matter a bottom unless the fencing is secured to the ground, in which case the ground is the bottom.
This is an example of an opinion about what the law says with an eye toward making what someone wants 'fit' rather than looking at the actual law. Enclosed is enclosed completely. Secured is secured. Both must occur for the grow to pass legal challenge. To suggest otherwise on semantics to try and make something 'fit' puts people at risk. Anyone that simply fences in their outdoor grow should expect to make that argument from the defense table giving current rulings and common sense.
Dr. Bob