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Plenty of standards use shall, but never must, as their imperative word. For example (the first standard I had to hand) ISO 27001 has many occurrences of shall
(not capitalised, that seems to be an IETF special) and none of must. Shall is hard in English (outside standards). For a start there’s the shall/will issue, see for example
http://www.oxforddictionaries.com/words/shall-or-will (And where it says “In practice”, that may or may not be so if you have an editor or a customer with strong views. Or hold such views yourself.) But since standards are not written in the first person, when shall and will are differentiated, from that link, shall is “a strong determination to do something”.
Not quite that same as a standardese instruction (unless we view it as the strong determination of the instructor). Which all is why RFC 2119 exists. --
Christopher Dearlove BAE Systems Applied Intelligence Limited Registered Office: Surrey Research Park, Guildford, Surrey, GU2 7YP From: Ted Lemon [mailto:mellon@xxxxxxxxx]
*** WARNING ***
This message originates from outside our organisation, either from an external partner or the internet. The problem with SHALL is that in other contexts it often means MUST, which is kind of weird, and not really what the english word means. I tend to agree that it's worth advising against its use. On Thu, Aug 11, 2016 at 7:44 AM, Stewart Bryant <stewart.bryant@xxxxxxxxx> wrote: Optional is useful in a requirements RFC.
Grammatically, RECOMMENDED is sometimes useful, as using SHOULD instead can produce less clear sentences. In principal the same applies to OPTIONAL, but I've never had cause to use it. ******************************************************************** |