There are IFR (IR) and VFR (VR) routes as follows:  FAA Chart Users Guide - VFR Terms and Symbols 19 Temporary Flight Restriction (TFR) Areas Relating to National Security  are indicated with a broken blue line  . A Temporary Flight Restriction (TFR) is a type of Notice to Airmen (NOTAM). A TFR defines an area where  air travel is restricted due to a hazardous condition, a special event, or a general warning for the entire airspace. The text  of the actual TFR contains the fine points of the restriction. It is important to note that only TFRs relating to National Secu - rity are charted. Air Defense Identification Zones (ADIZs)  are symbolized using the ADIZ symbol:  . As defined in Code  of Federal Regulations 14 (CFR 14) Part 99, an ADIZ is an area in which the ready identification, location, and control of  all aircraft is required in the interest of national security. ADIZ boundaries include Alaska, Hawaii, Guam, Canada and the  Contiguous U.S. Terminal Radar Service Areas (TRSAs)  are shown in their entirety, symbolized by a screened black outline of the entire  area including the various sectors within the area  . The outer limit of the entire Terminal Radar Service Areas (TRSA) is a continuous screened black line. The various sec- tors within the TRSA are symbolized by narrower screened black lines. Each sector altitude is identified in solid black color by the MSL ceiling and floor values of the respective sector, elimi - nating the last two zeros. A leader line is used when the altitude values must be positioned outside the respective sec- tors because of charting space limitations. The TRSA name is shown near the north position of the TRSA as follows:  . Associated frequencies are listed in a table on the chart border. Military Training Routes (MTRs)  are shown on Sectionals and TACs. They are identified by the route designator: . Route designators are shown in solid black on the route centerline, positioned along the route for  continuity. The designator IR or VR is not repeated when two or more routes are established over the same airspace, e.g.,  IR201-205-227. Routes numbered 001 to 099 are shown as IR1 or VR99, eliminating the initial zeros. Direction of flight  along the route is indicated by small arrowheads adjacent to and in conjunction with each route designator. The following note appears on Helicopters, Sectionals and TACs except for Hawaiian Islands which is different. MTRs can vary in width from 4 to 16 miles. Detailed route width information is available in the Flight Information Publica- tion (FLIP) AP/1B (a Department of Defense publication), or through the 56 Day NASR Subscription from the National  Flight Data Center (NFDC). Special Military Activity  areas are indicated on Sectionals by a boxed note in black type. The note contains radio fre- quency information for obtaining area activity status. b. Routes above 1500' AGL (some segments of these routes may be below 1500') are identified by three or fewer  digit numbers; e.g., IR21, VR302, etc. These routes are developed for flight under Instrument Flight Rules. a. Routes at or below 1500' AGL (with no segment above 1500') are identified by four-digit numbers; e.g.,  VR1007, etc. These routes are generally developed for flight under Visual Flight Rules. Route identification: