###### Contents:
• I Control
• 1 Conventions

## Part I Control

### Conventions

\label{chap:conventions}

## Reference System

\label{sec:reference}

The accelerator and/or beam line to be studied is described as a sequence of beam elements placed sequentially along a reference orbit. The reference orbit is the path of a charged particle having the central design momentum of the accelerator through idealised magnets with no fringe fields (see Figure \ref{F-REF}).