: Re: Should one use the legal "shall" in requirements documents and specification documents? At least in the US, "will" has replaced "shall" in most every context, with the notable exception of the

@Steve161

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Option 1: use RFC 2119
According to RFC 2119:

MUST This word, or the terms "REQUIRED" or "SHALL", mean that the definition is an absolute requirement of the specification.

This is also the most current use of the word "shall" from what I've seen in the requirements.
Option 2: use present tense
If the requirements are mostly mandatory, you may also want to formulate the requirements in present tense, without "must", "shall" or other keywords. Example:

The undo history is preserved when the application is closed.

The requirement clearly states, by its present tense, that the requirement is mandatory. The history should be preserved, and if it's not, the software fails to pass this requirement.
Such way of writing the requirements allows them to be slightly more readable, without losing their mandatory property.
Option 3: use your own conventions
Note that you may define your own terminology in the documents you write. That's why most documentation starts by defining the terms, including "must", "can", etc. For example, HTTP specification contains such section: 1.2 Requirements.

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [34].
An implementation is not compliant if it fails to satisfy one or more of the MUST or REQUIRED level requirements for the protocols it implements. An implementation that satisfies all the MUST or REQUIRED level and all the SHOULD level requirements for its protocols is said to be "unconditionally compliant"; one that satisfies all the MUST level requirements but not all the SHOULD level requirements for its protocols is said to be "conditionally compliant."

Using a convention which differs a lot from the generally accepted practice is still a bad idea, and must be done only if you have serious reasons to do it.

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