See the reign of HENRY, in Ducange (Hist. de C. P. l. i. c. 35 - 41, l. ii. c. 1 - 22), who is much
indebted to the Epistles of the Popes. Le Beau (Hist. du Bas
Empire, tom. xxi. p. 120 - 122) has found, perhaps in
Doutreman, some laws of Henry, which determined the service
of fiefs, and the prerogatives of the emperor.