nonpaper, n.: This doesn’t sound like something that could exist, but it’s a document circulated informally for discussion in a multilateral environment with no identified source or attribution, and that doesn’t represent anyone’s official negotiating position.
no-host, adj.: Some kind of an event, usually a meal, where participants will pay their own way, as opposed to a “hosted” event where the person/organization inviting covers the costs.
OBE (Overtaken by Events), adj.: You were working frantically on a briefing paper or some other project, but then Something Happened to render all your hard work suddenly useless and irrelevant. Your project is OBE.
cable, n.: Once upon a time, many years ago, diplomatic messages were sent using the telegraph system. A whole set of terms related to official messaging rose up in these days of yore and the terminology has stuck around even though the technology has changed. A “cable” is therefore official for-the-record correspondence, as opposed to a regular old email.
reftel, septel, n. or adv.: These are both ways of referring in one cable to information discussed in more detail in another; “reftel” refers to a cable that has already been written, citing the appropriate reference number, while “septel” means the other cable hasn’t been written yet, but keep an eye out for it!
not/not, adv.: Back in the telegraph days cables were all submitted IN ALL CAPS, ALL THE TIME, JUST LIKE THIS. One of the limits of the technology. This made it hard to express emphasis, especially when you really wanted to tell the folks in Washington that whatever they’re thinking is totally and completely wrong. Some clever officer came up with the expression not/not, or NOT/NOT, as it was in the day, for when something is so not it’s worth saying twice. Since the State Department has made it to the 21st century we now have access to lowercase and fonts and bold and italics and other stylistic ways to show emphasis, but this phrase in particular has stuck around.