2.6 Grid facilities To assist in the positioning of entities
on a diagram, the user may turn on a grid in either
centimetres or inches, via an option on the control
panel. Initially, the grid is off. The grid may be turned on
and off at any time during an editing session and can be
toggled between inches and centimetres at any time. A
grid option will be provided on the reduce-to-fit view but
the number of grid lines shown will be reduced to avoid
filling the smaller diagram with grid lines.
Grid requirement mixes three different kinds of requirement.
• Conceptual functional requirement (the need for a grid).
• Non-functional requirement (grid units).
• Non-functional UI requirement (grid switching).