Incas used quipus for record-keeping. Knotted bundles of strings in which the number and spacing of knots, the colour and type of string were used. Some were literary where knots were combined with coloured rectangular signs or oval signs known as tocapus. Tocapus should be considered an ideographic system rather than writing. Many quipus with elaborate symbols were burned by the Spaniards, while others were hidden or disposed of by the Incas themselves.