What is a railing run ?

Runs:

A "run" is a section of railing between any two main start and end points.

For example the image below shows 4 runs.

A run can also be different sections of railing between any start and end point where the nature of the railing length or height needs to vary, for example the first 3 metres may be on level ground and then the next 3 metres on sloping ground requring stepped or raked railings, forming two railing styles and therefore two runs.