  Tool-assisted analysis of software systems and convenient guides to practise
the formal methods are still motivating challenges. This article addresses
these challenges. We ex periment on analysing a formal specification from
multiple aspects. The B method and the Atelier-B tool are used for formal
specifications, for safety property analysis and for refinements. The ProB tool
is used to supplement the study with model checking; it helps to discover
errors and there fore to improve the former specifications.
