Ind. Code § 9-21-18-11
A do not enter sign that is installed after July 1, 1990, to control the movement of vehicular traffic in an area subject to this chapter must meet the following requirements:
(2) The sign must be a square.
[Pre-1991 Recodification Citation: 9-4-1-29.1(d).]
As added by P.L.2-1991, SEC.9.