  The threats to security of the information originating owing to involuntary
operations of the users of a CAD, and methods of its protection implemented in
a complex CAD system of renovation of firms are considered: rollback, autosave,
automatic backup copying and electronic subscript. The specificity of a complex
CAD is reflected in necessity of rollback and autosave both of the draw and the
parametric representations of its parts, which are the information models of
the problem-oriented extensions of the CAD
