Three letter rule poets such as John Milton alternated between short and long forms for function words, depending on whether they occurred on or off the meter. For instance: While many function words have more than two letters ("and", "she", "were", "therefore", etc.), the exceptions to the rule are rather two-letter content words. Only a few of these occur commonly in most texts: the words "go" (which also has a functional usage in the idiom "going to do something"), "ox" and, especially in American texts, "ax". English grammar is relatively flexible about converting words of one class to another, allowing verbal uses such
Word polygon each word. Further rules may be set. One letter may be highlighted, and all words made must include that letter. A minimum length for words may be set. There is always at least one word that can be made using all of the available letters, and the rules may require that a maximum length word be found. With each puzzle, a number of words to aim for is usually included as a guide, with three difficulty ratings: good, very good and excellent. Each puzzle differs in its target, depending on the letters given to work with. In Australia, "The Advertiser"