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
Augmentative and alternative communication Rate enhancement strategies can increase the user's rate of output to around 12–15 words per minute, and as a result enhance the efficiency of communication. There are two main options for increasing the rate of communication: encoding and prediction. Encoding is a technique permitting an AAC user to produce an entire word, sentence or phrase using only one or two activations of their AAC system. In numeric, alpha-numeric, and letter encoding (also known as abbreviation-expansion), words and sentences are coded as sequences of letters and numbers. For example, typing "HH" may retrieve "Hello, how are you?". In iconic encoding strategies,