What is the point of SHOULD then?

(No seriously, I’m asking; are there examples of where it’s actually different from a MUST)?

Also this reminds me of something I read somewhere a long time ago: when specifying requirements don’t bother with SHOULD. Either you want it or you don’t. Because if it’s not a requirement, some people won’t implement it.

I guess the one time it’s good is if you want an optional feature or are moving towards requiring it. In this case Google has decided it’s not an optional feature.

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spongebobstoes 9 hours ago | parent | next [-]

SHOULD generally means: some people might require it. implement it for best results

backward compatibility makes it hard to add MUST. using SHOULD is a good alternative

	▲	Brian_K_White 4 hours ago \| parent [-]
		"SHOULD generally means: some people might require it." No it absolutely does not mean that. It means, by explicit definition which is right here, that text is exactly that definition, that no one requires it. They can't require it, and still be conforming to the spec or rfc. That's the entire point of that text is to define that and remove all ambiguity about it. It's not required by anyone. The reason it's there at all, and has "should" is that it's useful and helpful and good to include, all else being equal. But by the very definition itself, no people require it. No people are allowed to require it. Any that do, are simply violating the spec.

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phicoh 8 hours ago | parent | prev | next [-]

Typically, MUST means that if you don't do that then something will break at the protocol level.

SHOULD means that if you don't that, bad things are likely to happen, but it will not immediately break at the protocol level and during discussion in the IETF some people thought there could be valid reasons to violate the SHOULD.

Typically, IETF standards track RFCs consider the immediate effects of the protocol but often do not consider operational reality very well.

Sometimes operational reality is that a MUST gets violated because the standard is just wrong. Sometimes a SHOULD becomes required, etc.

Certainly for email, there is a lot you have to do to get your email accepted that is not spelled out in the RFCs.

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jagged-chisel 9 hours ago | parent | prev | next [-]

MUST means omission is unacceptable. SHOULD means MUST unless you have a good, well-reasoned excuse.

	▲	Brian_K_White 4 hours ago \| parent [-]
		Incorrect. Not required is not required. You do not need to supply rationale or get agreement by anyone else that your reasons are good in their opinion and not just in your opinion. Should just means the thing is preferred. It's something that is good and useful and helpful to do. That is not "must unless you can convince me that you should be excused".

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jolmg 3 hours ago | parent | prev | next [-]

I SHOULD have 8 hours of sleep every night. It's RECOMMENDED. However, there are times where it's best I don't (e.g. because of work, or travel, or needing to take someone to the hospital, etc.). It's definitely not that I MUST sleep 8 hours every night.

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nailer 9 hours ago | parent | prev [-]

“When jump getting over a wall, you SHOULD use three points of contact.”

For most cases you should use three points of contact. However, there may be other situations for example if someone is giving you a leg up, or you can pole vault, where another solution is preferred.