It repairs files damaged by all currently known strains of the nVIR virus (including Hpat). It can even clean the currently active System File and so can be used even if no clean System is available. As it has no detection features, it should be used with a program such as Virus Rx.
Since its resource fork is locked it should not be able to be infected on disk. It also claims to be immune from infection by nVIR in memory as well.