the edge of the flag) had not been officially fixed prior to 2017. The annex to the flag law provides an image specifying that the margin is to be of the same width as the cross arms, so that the total height of the cross is fixed at 20:32 = 5:8 of the height of the flag (in other words, the width of the margin is 6:32 = 3:16). This ratio is also given as a "vexillological recommendation" in the flag regulation used by the Swiss Armed Forces. Flags with a cross of larger relative widths than the prescribed 20:32 = 62.5% remain in wide use; common ratios include 20:26 ≈ 76.9% and 20:28 ≈ 71.4%. For the ensign, the ratio of the size of the cross to the height is likewise 5:8, so that the ratio of cross to flag width is 5:12. Colors The shade of red used in the flag was not defined by law prior to 2017. Since then, the colour of the flag is defined as pure red, with the color values as follows: History Middle Ages The ultimate origin of the white cross is attributed by three competing legends: To the Theban Legion, to the Reichssturmfahne (Imperial War Banner) attested from the 12th century, and to the Arma Christi that were especially venerated in the three forest cantons, and which they were allegedly allowed to display on the formerly uniformly red battle flag from 1289 by king Rudolph I of Habsburg at the occasion of a campaign to Besançon. Use of a white cross as a mark of identification of the combined troops of the Old Swiss Confederacy is first attested in the Battle of Laupen (1339), where it was sewn on combatants' clothing as two stripes of textile, contrasting with the red St. George's cross of Habsburg Austria, and with the St. Andrew's cross used by Burgundy and Maximilian I. The first flag used as a field sign representing the confederacy rather than the individual cantons may have been used in the Battle of Arbedo in 1422 (notably without the participation of the Canton of Schwyz). This was a triangular red flag with an elongated white cross. The white cross was thus in origin a field mark attached to combatants for identification, and later also to cantonal flags. The Lucerne chronicle of 1513, in battle scenes of the Burgundy wars of the 1470s