Link: RFC 6919: Further Key Words for Use in RFCs to Indicate Requirement Levels
If you read RFCs, you may know about the standard use of the MUST, SHOULD, and so on key words that come from RFC 2119. RFC 6919, issued April 1st 2013, adds some useful additional key words like "MUST (BUT WE KNOW YOU WON'T)", "REALLY SHOULD NOT", and the like.
By itself this would be amusing and interesting. But what really makes RFC 6919 rewarding to read is that it shows usage examples for each of its new key words that are drawn from existing RFCs. If you have much exposure to how RFCs are actually implemented in the field, this will make you alternate laughter and sad sighs. To quote myself from when I first saw it:
RFC 6919 makes me laugh but it's sad laughter. Such honesty had to be published Monday.