void addFragSet( FragKind kind, int offset, BitSet bs, String frag )
    {
        this.versions.or(bs);
        if ( this.offset == -1 )
            this.offset = offset;
        this.state = SectionState.state(kind);
        for (int i = bs.nextSetBit(1); i>= 0; 
            i = bs.nextSetBit(i+1))
        {
            if ( lists.containsKey((short)i) )
            {
                FragList fl = lists.get( (short)i );
                fl.add( kind, frag, bs );
            }
            else
            {
                FragList fl = new FragList();
                fl.add( kind, frag, bs );
                lists.put( (short)i, fl );
            }
        }
    }