Segment A is chosen by cutting the chain at two points, x and y.
Therefore, B can consist of up to two segments, 
and
, depending on the positions of the boundaries.
The split value is calculated for all possible
segment A's formed by varying x and y. The
maximum split value is stored, together with the corresponding
values of x and
y, called 
and 
, which define 
.
The maximum split value is compared with MSV and if 
is not correlated with 
, then 
can be `extracted' from the `parent' domain to form a new
`child' domain (also referred to as a `subdomain'). The treatment
of 
is the same for all three scans and is shown at the end
of method 3.
Note that the single segment scan would be able to deal with both the situations that arise in Figure 1a and Figure 1b. However, it would not be able to deal with the case shown in Figure 1c. To allow for this eventuality a two segment scan is used.
