A reflective article has a multilayer film covering a patterned retroreflective layer. In one embodiment the patterned retroreflective layer includes a separate indicia layer covering a retroreflective substrate. The indicia are substantially hidden under normal viewing conditions but easily detectable...http://www.google.ca/patents/US6024455?utm_source=gb-gplus-sharePatent US6024455 - Reflective article with concealed retroreflective pattern
