6 Advances in spoken discourse analysis
Working downwards, each rank is first labelled. Then the elements of
structure are named, and the structure is stated in a general way, using
shortened forms of the names of elements. Brackets indicate structural
options.
The link between one rank and the next below is through classes. A class
realizes an element of structure, and in this summary classes are both numbered
and named. Let us look at one of the tables as an example:
This table identifies the rank as second from the top of the scale, i.e.
transaction. It states that there are three elements of structure, called
Preliminary (symbol P), Medial (M), and Terminal (T). In the next column
is given a composite statement of the possible structures of this transaction:
PM (M^2 ...Mn) (T). Anything within brackets is optional, so this formula
states:
(a) there must be a preliminary move in each transaction,
(b) there must be one medial move, but there may be any number of
them,
(c) there can be a terminal move, but not necessarily.
In the third column the elements of transaction structure are associated with
the classes of the rank next below, exchange, because each element is realized
by a particular class of exchange. Preliminary and terminal exchanges, it is
claimed, are selected from the same class of move called Boundary moves,
and this is numbered for ease of reference. The element medial is realized
by a class of exchange called Teaching. Later tables develop the structure
of these exchanges at rank III. There now follows the presentation of the
whole rank scale.
RANK II: Transaction
RANK I: Lesson