see SYNOPSIS
        my $o_m_parser = New MobyleParser($xmlfile, $special_cfg);

Procedure __GetHead

        Title      :    __GetHead
        Usage      :    __GetHead( $twig, $elt );
        Prerequiste:    launch by __ParseHeadElement uniquely
        Procedure  :    extract information from the unique Head element of the XML
        Args       :    $twig, a twig object
                        $elt, a twig elt object
        Error      :    none
        Globals    :    none

Procedure __CheckParameter

        Title      :    __CheckParameter
        Usage      :    __CheckParameter( $elt, $argpos );
        Prerequiste:    none
        Procedure  :    will set $self->{$type}{$name} with $rh
                        where $type is CMD|ENTREE_1R|ENTREE_2R|SORTIE
                                $name is the name of the parameter
                                $rh is a ref_hash containingall information read
                                        into the parameter element.
        Args       :    $elt a twig elt object which should be 'parameter'
                        $argpos, the position inherited from upper elements
                                it seems that it is not used, and in the fact
                                it have not be tested
        Error      :    none
        Globals    :    none

Procedure AdjustPosition

        Title      :    AdjustPosition
        Usage      :    $self->AdjustPosition();
        Prerequiste:    none
        Procedure  :    Change the bin_cmd attribute from a ref_hash to a string.
                        After the function, bin_cmd will be the masked command to launch program.
        Error      :    none