From Lehman's zoning dictionary
Sign, Electronic Message Board means any sign that uses changing lights, or other electronic media, to form a sign message or messages wherein the sequence of messages and the rate of change is electronically programmed and can be modified by an electronic process.
There are others in the dictionary as well, but this one seemed clearest and easiest. We'll be using it sometime this year when teh revisions are done.
Here are the provisions I scabbed together from other by-laws
ELECTRONIC MESSAGE BOARD
5.4.11 Electronic Message Board signs shall be permitted in the Highway Commercial (HC), Shopping Centre (SC), Institutional (IN), University Community College (UC) Mixed Use (MU) and all Industrial Zones, subject to the following:
a)not exceed 8.0 square metres in total area;
b)there be no scrolling or flashing of any portion of the message;
c)each message, or portion of message be displayed for no less than one minute;
d)that the maximum length of time between changes of messages, or portion of messages be not more than two seconds;
e)shall be located no closer than 100 metres from any illuminated traffic control device; and
f)may not exceed more than one per lot.