Capable of being allowed
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.
For the logical inquiry, however, it is permissible to ignore or reduce these differences.
He would sometimes regret that it was no longer permissible to leave it in the old Roman fashion.