Rusty, my dictionary has Revised 13th Edition on both the front and the spine, and also on the first inside page. My 12th edition simply says '12th edition' - so I expect the missing words one probably just has '13th edition' on it. I've been referring to 'grey words', just for ease - basically it's just shaded grey boxes on the page, the boxes containing unusual words and their definitions. Chambers says some of these words are rare, literary and historical, and others are intriguing or charming - that's why they've been highlighted. They slot in, alphabetically, with the words above and below them - for example 'flimp' is after 'flimflam' and before 'flimsy'.