There are four basic types of iconographic representations of the cross: the crux quadrata, or Greek cross, with four equal arms; the crux immissa, or Latin cross, whose base stem is longer than the other three arms; the crux commissa, in the form of the Greek letter tau, sometimes called St. Anthony’s cross; and the crux decussata, named from the Roman decussis, or symbol of the numeral 10, also known as St. Andrew’s cross for the supposed manner of the martyrdom of St. Andrew the Apostle. Tradition favours the crux immissa as that on which Christ died, but some believe that it was a crux commissa. The many variations and ornamentations of processional, altar, and heraldic crosses, of carved and painted crosses in churches, graveyards, and elsewhere, are developments of these four types.Cross forms were used as symbols, religious or otherwise, long before the Christian Era, but it is not always clear whether they were simply marks of identification or possession or were significant for belief and worship. Two pre-Christian cross forms have had some vogue in Christian usage. The ancient Egyptian hieroglyphic symbol of life—the ankh, a tau cross surmounted by a loop and known as crux ansata—was adopted and extensively used on Coptic Christian monuments. The swastika, called crux gammata, composed of four Greek capitals of the letter gamma, is marked on many early Christian tombs as a veiled symbol of the cross.