It would not be useful (unless you are doing research on the subject) to go into all the different ways in which English intonation has been represented, but it is worth noting that simpler approaches have been used in the past. In the earlier part of the last century, a common approach was to treat all the pitch movement in the tone-unit as a single "tune"; Tune l was typically descending and ending in a fall, while Tune 2 ended up rising (I was taught French intonation in this way in the 1960s). In more modern work, we can see that it is possible to represent intonation as a simple sequence of tonic and non-tonic stressed syllables, and pauses, with no higher-level organization; an example of this is the transcription used in the Spoken English Corpus (Williams, 1996). Brown (1990) uses a relatively simple analysis of intonation to present valuable examples of authentic recorded speech. Most contemporary British analyses, however, use a unit similar or identical to what I call a tone-unit divided into components such as pre-head, head, tonic syllable and tail. Different writers use different names: "tone-group", "intonation group", "sense-group", "intonation unit" and "intonation phrase (IP)" are all more or less synonymous with "tone-unit". Good background reading on this is Cruttenden (1997: 26-55).