title: CAT I
text: # CAT I
  
  CAT I may refer to:
  
  * Instrument landing system#ILS categories
  * Chloramphenicol O-acetyltransferase I, an enzyme
  * Carnitine O-palmitoyltransferase I, another enzyme
  * Measurement category CAT I, a class of live electrical circuits used in measurement and testing
  