* @param b an element of the transformation matrix
     * @param c an element of the transformation matrix
     * @param d an element of the transformation matrix
     * @param e an element of the transformation matrix
     * @param f an element of the transformation matrix
     **/
    public void concatCTM(final float a, final float b, final float c, final float d, final float e, final float f) {
        content.append(a).append(' ').append(b).append(' ').append(c).append(' ');
        content.append(d).append(' ').append(e).append(' ').append(f).append(" cm").append_i(separator);
    }