The ``Equation'' environment is defined as having an optional argument used as a label. The ``MultiLine'' environment is used for long formulas that don't fit on a single line, but no ampersand mark is needed, since all lines but the first are authomatically indented by a predefined amount of space. The ``System'' environment is for grouping a set of equations with one number and with an enclosing left brace. These two environments also have an optional argument used as a label. All the above environments have a *-form, which does not generate a number. The author is Francesco Bosisio.