in case of (an) emergency

0 No, you don't need 01i00an02i00, but omitting it is more characteristic of official announcements, such as those found in hotel rooms. In ordinary conversation, you're just as likely or maybe even more likely to hear 01i00in case of 01b00an02b00 emergency02i00.02br
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00 CJ0-

0CalifJim, I guess when you choose to use 'emergency' without 'an', the word 'emergency' is treated as a context/category, while 'an emergency' refers to one particular incident of emergency, for example, fire, flood and etc. Of course, in this case, the difference is trivial but I would like to know if my understanding is correct.02br
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00Could you please correct me if I'

0 It's less a matter of category vs. single incident and more a matter of 'telegraphic style', in my opinion. Official announcements typically omit articles. It's the same with newspaper headlines. There, too, articles are omitted for the sake of brevity. Even in the hotel room instructions, 01i00in case of emergency02i00 actually 01u00means02u0