From the Privacy Act Online via GPO Access [wais.access.gpo.gov] [DOCID:tres_irs-99]

DEPARTMENT OF TREASURY Treasury/IRS 60.001 System name: Assault and Threat Investigation Files, Inspection--Treasury/IRS. System location: Office of the Chief Inspector, National Office; Regional Inspectors' Offices; as well as offices of the District Directors. (See IRS appendix A for addresses.) Categories of individuals covered by the system: Individuals attempting to interfere with the administration of Internal Revenue laws through threats, assaults or forcible interference of any officer or employee while discharging the official duties of his position, or individuals classified as potentially dangerous taxpayers, based on verifiable evidence or information that fit the following criteria: (1) Taxpayers who physically assault an employee; (2) taxpayers who have on hand a deadly or dangerous weapon when meeting with an employee and it is apparent their purpose is to intimidate the employee; (3) taxpayers who make specific threats to do bodily harm to an employee; (4) taxpayers who use animals to threaten or intimidate an employee; (5) taxpayers who have committed the acts set forth in any of the above criteria (1) through (4), but whose acts have been directed against employees of other governmental agencies at Federal, state, county, or local levels; (6) taxpayers who are not classifiable as potentially dangerous through application of the above criteria (1) through (5), but who have demonstrated a clear propensity toward violence through acts of violent behavior to a serious and extreme degree within the five (5) year period immediately preceding the time of classification as potentially dangerous; and (7) persons who are active members in chapters of tax protest groups that advocate violence against IRS employees. ...