Railsign

Railsign is a secret marking system used by The Railroad. Each marking consists of an "asterisk" of six white lines, at the center of which is a special symbol. A visual chart of the railsigns appears in Railroad HQ

Symbols

 * Plus (+) - Ally - denotes an ally is present nearby.
 * Square - Cache - a supply cache can be found nearby.
 * X - Danger - warns that danger is present nearby.
 * Arrow - Pointer - shows the direction to something important.
 * House - Safehouse - a Railroad safehouse is nearby.
 * Teardrop - Dead drop - a Railroad dead drop is nearby.