A no parking sign was a sign that prohibited the parking of automobiles in the area indicated by the sign.
In 1968 New York City, Roberta Lincoln passed near a no parking sign which had been erected by the NYPD . (TOS: "Assignment: Earth")
In 2268, there was a no parking sign, which also prohibited commercial traffic, in front of a used furniture store on Sigma Iotia II. (TOS: "A Piece of the Action")