accent of the General American type, which is associated with a geographically "neutral" or widespread sound system throughout the US. Wells classifies English words into 24 lexical sets on the basis of the pronunciation of the vowel of their stressed syllable in the two reference accents. Typed in small caps, each lexical set is named after a representative keyword. Wells also describes three sets of words based on word-final unstressed vowels, which, though not included in the standard 24 lexical sets (the final three sets listed in the chart below) "have indexical and diagnostic value in distinguishing accents". For example, the word rod is pronounced in RP and in GenAm. It therefore belongs in the lexical set. Weary is pronounced in RP and in GenAm and thus belongs in the lexical set. Some English words do not belong to any lexical set. For example, the a in the stressed syllable of tomato is pronounced in RP, and in GenAm, a combination that is very unusual and is not covered by any of the 24 lexical sets above. The GenAm pronunciation of words pronounced with before a velar consonant in RP, such as mock and fog, varies between and and so the words belong to no particular lexical set. The GenAm , , , and range between monophthongal and diphthongal , and Wells chose to phonemicize three of them as monophthongs for the sake of simplicity and as to avoid confusion with RP , . The happ set was identified phonemically as the same as for both RP and GenAm, reflecting the then-traditional analysis, although realizations similar to (happy tensing) were already taking hold in both varieties. The notation for happ has since emerged and been taken up by major pronouncing dictionaries, including Wells's, to take note of this shift. Wells's model of General American is also conservative in that it lacks the cot–caught (–) and horse–hoarse (–) mergers. Choice of the keywords Wells explains his choice of keywords ("kit", "fleece", etc.) as follows: The keywords have been chosen in such a way that clarity is maximized: whatever accent of English they are spoken in, they can hardly be mistaken for other words. Although fleece is not the commonest of words, it cannot be mistaken for a word with some other vowel; whereas beat, say, if we had chosen it instead, would have been subject to the drawback that one man's