their vehicle (normally in accordance with the rules of the state of issuance). Recognition and reciprocity of concealed carry privileges varies. Some states (e.g. Indiana, Virginia, Ohio) unilaterally recognize all permits. Others such as Michigan, limit such universal recognition to residents of the permit-issuing state. While 37 states have reciprocity agreements with at least one other state and several states honor all out-of-state concealed carry permits, some states have special requirements like training courses or safety exams, and therefore do not honor permits from states that do not have such requirements for issue. Some states make exceptions for persons under the minimum age (usually 21) if they are active or honorably-discharged members of the military or a police force (the second of these two is subject additionally to federal law). States that do not have this exemption generally do not recognize any license from states that do. An example of this is the state of Washington's refusal to honor any Texas LTC as Texas has the military exception to age. Idaho, Mississippi, North Dakota, South Dakota, and Tennessee have standard and enhanced permits that have different requirements to obtain and also have unique reciprocity with different states; Utah and West Virginia have provisional permits for 18-20 year olds with more limited recognition by other states. Permits from Idaho (enhanced), Kansas, Michigan, and North Dakota (class 1) have the highest number of recognition by other states (39 states). One can obtain multiple state permits in an effort to increase the number of states where that user can carry a legally concealed weapon. It is common practice to use a CCW Reciprocity Map to gain clarity on which states will honor the person's combination of resident and non-resident permits given the variety of standards and legal policies from state to state. There are also various mobile applications that guide users in researching state concealed carry permit reciprocity. Although carry may be legal under State law in accordance with reciprocity agreements, the Federal Gun Free School Zones Act subjects an out-of-state permit holder to federal felony prosecution if they carry a firearm within 1000 feet of any K–12 school's property line; however, the enforcement of this statute is rare given several states' nullification statutes prohibiting state law enforcement officers from enforcing federal firearms laws. However, states may have their own similar statutes that such officers will enforce, and potentially expose the carrier to