jarl ‘the jarl [Sveinn Úlfsson]’: Sveinn Úlfsson, son of the Dan. jarl Úlfr Þorgilsson and of Ástríðr, sister of Knútr inn ríki, hence known also as Sven Estridsson. Appointed Magnús’s viceroy over Jylland, he broke his oaths of loyalty and attempted to establish himself as king (e.g. MgóðHkr ch. 25, ÍF 28, 40-1). See also ÞjóðA Magnfl 5 and ‘Royal Biographies’ in Introduction to this vol.