A model mapping which we shall consider consists
of a piecewise linear system on the interval (0,1) with 4 straight
line sections. The system is sketched in Figure 1
Inside the centrally placed square box of side 
(which we term The region of the Feature)
is placed a Feature, which can
be either a trap or a snag.
The size of the Feature and its region can be made
arbitrarily small. The mapping is described
mathematically by the following set of equations:-
Here, F(x) is the mapping of the Feature, which is discussed below.
Figure 1: The mapping containing the Feature.