\begin{definition}[Definition:Imperial/Length/Chain]
The '''chain''' is an imperial unit of length.
{{begin-eqn}}
{{eqn | o = 
      | r = 1
      | c = '''chain'''
}}
{{eqn | r = 4
      | c = rods, poles or perches
}}
{{eqn | r = 22
      | c = yards
}}
{{eqn | r = 66
      | c = feet
}}
{{eqn | r = 20 \cdotp 1168
      | c = metres
}}
{{end-eqn}}
\end{definition}