This may not be logical, but long usage has made it permissible or even necessary.
As a rule it is not permissible to erect a building wider than the road, measured from building line to building line.
Voluntary enlistments in the French army are permissible, within certain limits, at the age of eighteen, and the engages serve for at least three years.
Civil marriages have been permissible in Hamburg since 1866, and since the introduction of the imperial law in January 1876 the number of such marriages has greatly increased.
The permissible phosphorus-content is lessened by the presence of either much sulphur or much manganese, and by rapid cooling, as for instance in case of thin castings, because each of these three things, by leading to the formation of the brittle cementite, in itself creates brittleness which aggravates that caused by phosphorus.