+ <boolean id="sco" _label="SCO" arg-unset="-no-sco"/>
+ <boolean id="hvx" _label="HVX/GCOS6" arg-unset="-no-hvx"/>
+ <boolean id="hpux" _label="HPUX" arg-unset="-no-hpux"/>
+ <boolean id="amiga" _label="AmigaDOS" arg-unset="-no-amiga"/>
+ <boolean id="atari" _label="Atari" arg-set="-atari"/>
+ <boolean id="apple2" _label="Apple II" arg-unset="-no-apple2"/>