Each item has a set of features which describe its local properties. Values of features can be real values or functions. A relation links together items of a common linguistic type . For instance there we might have a word, phone, syntax or syllable relation. Relations are general graph structures, the most common type being a simple doubly linked list.
Relations can also take the form of trees.
For example, we have a syllable structure relation which gives onset, coda, nucleus and rhyme structure for a syllable. The crucial aspect of the Festival architecture is that items can be in more than one relation. For example, a syntax relation is a tree whose terminal elements are words, which are also in the word relation. Utterances Utterances contain a list of all the relations. These examples are drawn in Fringe, a graphical tool under development for use with festival.