requires several weeks of intravenous antibiotics. During the treatment period, these patients can use the central intravenous line or peripherally inserted central line (PICC) to inject narcotics or other illicit drugs. Evidence exists that applying a tamper-evident device to the central line can deter illicit use of the line. Security packaging is needed to contain evidence of crimes. Items must be kept in an unaltered state until they are submitted in a legal proceeding. Packaging that tears open raggedly or otherwise cannot readily be resealed is sometimes used to help indicate tampering. Often, multiple layers or redundant indicators are used because no single layer or device is "tamper-proof". Consideration should be given to unique custom indicators (which should be changed regularly because these are subject to counterfeiting). People who open secure packaging can look out for signs of tampering, both at the primary means of entrance and at secondary or "back door" locations on a package. Credit cards, money, stamps, coupons In financial terms, tamper-evident design overlaps a lot with anti-forgery techniques, as ways to detect monetary tokens which are not what they seem. Postage stamps, for example, may contain a layer of ultraviolet-reflective ink which changes state under pressure. The impact from a postmarking machine then leaves a UV-visible mark as well as an ink mark which identifies attempts to reuse stamps. In a similar vein, asset-numbering labels on corporate equipment (PCs and the like) are often designed to leave an imprint of either the serial number, or the word "VOID" if the label is peeled off. However, this can easily be defeated by warming up the label using a blow dryer so it will be more flexible and forgiving to removal (and reapplication). Road tax vignettes and price tags are often tamper-evident in the sense that they cannot be removed in one piece. This makes it difficult to move a vignette from one car to another, or to peel off a price tag from a cheaper article and reapply it to a more expensive one. Money is tamper-evident in the sense that it should be difficult to produce a financial token without authorization, even if starting from a token of lower value. For example, forgers may attempt to clean the ink from a banknote and print the image of a higher-denomination note on it, giving them the carefully guarded "banknote paper" which is otherwise very difficult to obtain.