The 'jugum' was probably originally taken from the area which could be cultivated by the single or double yoke of oxen allotted to the settler, and may [p290] have been a single or double one accordingly. But a person holding a fraction of a _jugum_ or _caput_ was said to hold only a '_portio_,'[421] and paid, in consequence, a proportion only of the burdens assessed upon the whole jugum. Now, if the taxation had continued at actually so much per yoke of oxen, the system would have been simple enough; and it would be easy to understand how, whilst the _jugum_ represented the unit of taxation for land, the _caput_ might be the unit corresponding in value with the jugum, but applying to other kinds of property, such as slaves and cattle, and including the capitation tax levied in respect of wives and children. And this, probably, may be the meaning of the double nomenclature--_jugum vel caput_. At any rate, we know from the Theodosian Code, that the members of a veteran's family were constituent parts of his 'caput.'[422] The subject is obscure, but the reform of Diocletian seems to have aimed at an equalisation of the taxation according to the value of property. «The _jugum_ became a unit of taxation,» This seems to have involved an assessment of various kinds of land in hypothetical _juga_, of the same value (said to be fixed at 2,000 solidi); and this involved a variation in the acreage of the hypothetical _jugum_, according to the richness or otherwise of the land, just as according to Flaccus was the case also as regards the actual centuriæ and allotments. «and varied in area.» In one instance in which the figures have been [p291] preserved, viz. for Syria, under the Eastern Empire, the assessment was as follows under the system of Diocletian:[423]-- Of vine-land 5 jugera, or 10 plethra or half-acres. Arable, first class 20 jugera, or 40 plethra or half-acres. Arable, second class 40 jugera, or 80 plethra or half-acres. Arable, third class 60 jugera, or 120 plethra or half-acres. In the east, therefore, sixty jugera, or 120 Greek plethra or half-acres, of ordinary arable land, were assessed as a _jugum_. This instance makes it clear that while originally the actual allotment to a single or double yoke of oxen may have been taken as the basis of taxation, the 'jugum' had already become a hypothetical _unit of assessment_, just as, by a similar process, was the case with the English hide. Property had come to be assessed at so many _juga_ under the _jugation_, without any attempt to make the assessment accord with the actual number of yokes employed. «The Indiction.» The assessment was revised every fifteen years at what was called the _Indiction_.[424] We have seen that the nominal acreage of the typical holding assigned to the single yoke of two oxen under Roman law on the Continent resembled very closely that of the Saxon yard-land, which also had two oxen allotted with it.[425] [p292]