The ICAO aircraft type designators for the three variants are "BE35", "BE33", and "BE36" respectively. Laser designators/range finders are also used to designate the target for the missile to hit. In 1948 the use of suffix letters in squadron designators was discontinued. In general, the categories are the same but criteria for the numerical designators may differ. He called such directly referring proper names "rigid designators". The type designators of semiconductor devices are often manufacturer specific. Kripke refers to names used in this way as rigid designators. The actual speeds represented by these designators are specific to a particular model of aircraft. The table below lists designators commonly used, and does not necessarily comply with standards. Laser designators work best in clear atmospheric conditions. A removable bipod, rails for designators, sling, etc. The respective GRAU designators are 52-P-482 and 52-P-547. Confusingly, the model designators for the US now reverted to TR6R and TR6C. This is a list of naval officer designators in the United States Navy. There is some confusion on ship designators within even official records.