  The long term aim of the project carried out by the French National Space
Agency (CNES) is to design a writing guide based on the real and regular
writing of requirements. As a first step in the project, this paper proposes a
lin-guistic analysis of requirements written in French by CNES engineers. The
aim is to determine to what extent they conform to two rules laid down in
INCOSE, a recent guide for writing requirements. Although CNES engineers are
not obliged to follow any Controlled Natural Language in their writing of
requirements, we believe that language regularities are likely to emerge from
this task, mainly due to the writers' experience. The issue is approached using
natural language processing tools to identify sentences that do not comply with
INCOSE rules. We further review these sentences to understand why the
recommendations cannot (or should not) always be applied when specifying
large-scale projects.
