Blue signs with lettering typically indicate informational signage, such as signs for rest areas, hospitals, or service facilities. They are often used for direction and guidance purposes on highways and roadways.
In F1 and most circuit racing, blue flags are used to indicate to a driver that a faster car is approcahing from behind to lap him. The driver is then expected to yield. Blue flags(some places, blue lights) are also used at the pit exit, to indicate to drivers leaving the pit, that there is a car approaching on the track.
Gas signs on highways are usually red, blue, and white. Red is often used for prices and text, blue for background or borders, and white for contrast or accents. These colors are chosen for their visibility and ability to catch the attention of drivers.
Brown signs are used to indicate points of interest such as parks, historical sites, and cultural attractions. They typically represent tourist attractions and recreational areas.
The white lettering and symbols on the surface of the roadway are road markings and signs that indicate important information to drivers, such as speed limits, lane assignments, pedestrian crossings, or upcoming exits. They are used to guide and control traffic flow, improve road safety, and provide important information to drivers.
A blank line before the major heading and a blank line after the heading is an indicator on the document as the heading. And the number signs used to indicate numbers are dots.
Democrat.
Stop signs
brown
disabled parking
There are a wide range of road signs that are used for various reasons. There are stop signs to warn people to stop at intersections, Yield signs so that one will yield to oncoming traffic, Deer Crossing signs to warn of areas where there might be deer crossing the road as well as Speed Limit signs to warn drivers of the allowed speed in a designated area.
No, there is no such requirement or convention.