I received the following from on a Yahoo Group:

"There are two definitions of clothing optional. One is that it means you have the option to keep your clothes on.The second is that it means you have the option to take all your clothes off."
We were asked for our opinions. Here is my response:

Both definitions apply.

Since generally the term "clothing-optional" is used in a textile world, one understands that most people arrive wearing clothes but are allowed to remove them. Obviously, one is not required to remove one's clothing so as to exercise the option to redress.

In a nudist resort, most people still arrive clothed, but the emphasis is that one would have the option to remain clothed. Again, one is not expected to get naked first so as to exercise the option of again wearing clothes; nor, if one arrived nude (as I often do) would I be expected to get dressed so as to exercise my option to get naked.

In a naturist resort, the term "nudity optional" might be more appropriate, though C/O and N/O are exactly synonymous - that is, they mean the very same thing, not merely nearly the same thing. For example, my house is "C/O" and "N/O". No matter what perspective one comes from (nudist or textilist), either term means that in my house residents and guests can wear clothes (any amount) or no clothes - and can do so regardless of the preferences of others in the house. For practical purposes, the sign on my door states "clothing-optional", but it could just as well read "nudity optional".

A naturist beach is, ipso facto, a clothing-optional beach. To my knowledge, there is but one public nude beach (which is in Brazil). All other public beaches are either "clothing required" (amount of clothing subject to culture and law) or "clothing optional". I know of no other public beach where nudity is required. Many private nudist resorts, of course, are "nudity required" which is why I say "nudity optional" makes sense for private naturist resorts.

When advocating for or otherwise addressing public officials or the media about naturist beaches, I refer to them as "clothing-optional" or sometimes "nude optional" but never as "nudist" or "nude' so as to emphasize that the beaches, whether proposed or extant, are open to all citizens regardless of their personal preferences for clothing - unlike textile beaches which are reserved for the religiously or irrationally modest only.

(Footnote: I am purposefully distinguishing between those who are clothing modest because their religion demands it and clothing modest for no known reason. One can argue that religious proscriptions against nudity are irrational, but a person adhering to religiously based restrictions at least has a reason for wearing a swimsuit (or more) on a beach. Most people can't formulate any reason whatsoever, they just are compelled to follow the clothing standards of the culture. (Thus many males now feel uncomfortable wearing a swimsuit that doesn't extend to the knees, despite the impracticality of such a suit. On my occasional visit to textile beaches, I am the only swimmer in a Speedo style suit.) In arguing for a naturist beach, point out that neither the state nor others on the beach should be determining the amount and style of clothing for anyone else. There should be no minimum standard. Nudity should be no more prohibited than Speedos just because others are uncomfortable that way -- whether their uncomfortableness is due to religious, personal, or cultural irrationality -- or think others look ridiculous nude or in Speedos. If the authorities insist on textile beaches, they should also provide naturist beaches or get Sharia Law established as the basis of all laws.

Footnote two: I purposely used "clothing" as an attributive noun (an attributive noun is merely a noun used as a modifier of another noun) before "modesty". When discussing naturist beaches with the media or public officials or anyone, we need to emphasize that naturists expect clothing-optional beaches to maintain standards of behavior equal to or exceeding that of the textile beaches. (Since some textile beaches are notorious for the prevalence of immodesty - excessive alcohol consumption and salacious behavior, make the point that clothing does not guarantee modesty - in fact, much legal clothing on the beaches are designed to be sexually stimulating.) Make the point that official, clothing-optional beaches are family friendly. When nudity is confined to some remote spot, then it attracts yahoos that think anything goes. Naturists want to be insulated from these yahoos and having official, reasonably regulated (i.e. occasional police surveillance, nearby lavatories, refreshment stands), keeps the yahoos over at the notorious textile beaches where they belong.) In other words, neither "clothing-optional" nor "nudity-optional" means "anything goes".