!!! Overview
[{$pagename}] is a [RFC] describing Key words for use in [RFCs] to Indicate Requirement Levels

[We refer you to the full text|RFC:2119|target='_blank'].

%%warning
[RFC 8174] updates [{$pagename}] by clarifying that only __UPPERCASE__ usage of the key words have the __defined special meanings__.  [RFC 8174] document is part of [BCP 14].
%%[{$pagename}] includes: (Terms on the same line imply the same meaning)
* [MUST], [REQUIRED], [SHALL]
* [MUST NOT], [SHALL NOT]
* [SHOULD], [RECOMMENDED]
* [SHOULD NOT], [NOT RECOMMENDED]
* [MAY], [OPTIONAL]

!! Guidance in the use of these Imperatives
Imperatives of the type defined in this memo [MUST] be used with care and sparingly.  In particular, they [MUST] only be used where it is actually required for interoperation or to limit behavior which has potential for causing harm (e.g., limiting retransmissions)  For [example], they [MUST NOT] be used to try to impose a particular method on implementers where the method is not required for interoperability.

!! [Security Considerations]
These terms are frequently used to specify behavior with security implications.  The effects on security of not implementing a [MUST] or [SHOULD], or doing something the specification says [MUST NOT] or [SHOULD NOT] be done may be very subtle. Document authors should take the time to elaborate the [security implications|Security Considerations] of not following recommendations or requirements as most implementers will not have had the benefit of the experience and discussion that produced the specification.

!! More Information
There might be more information for this subject on one of the following:
[{ReferringPagesPlugin before='*' after='\n' }]