in the equation of a straight line, 
[P1.3]
of: a straight line
is: the constant in the equation of a straight line, [P1.3]
therefore is: the value of 
when 
i.e. the point at which the straight line crosses the -axis. [M2.2, M3.1, P1.3]
more generally refers: to the common point of two straight lines that intersect. [M2.1]
Copyright 1997, The Open University