Making levels of danger obvious

I'm working on a monitoring system: it sends messages, each message has a danger/severity flag and I want it to be very obvious for even a casual user. Which of the following have obvious meanings, and is it possible to name a seq开发者_StackOverflow中文版uence of level names that will absolutely mean gradations of danger for every sane computer-literal human (i.e. for a given (A, B, C, D, ...) any human would instantly recognize that A is less dangerous that B, B is less dangerous than C, C < D, etc).

I've seen a couple of possible danger levels gradations, but I'm not sure how obvious it is for a casual user:

• OK
• INFO
• WARNING
• ERROR
• FAILURE
• CRITICAL
• FATAL
• GRAVE

Which sequence of severity / danger levels would be most obvious for every user in the world? For example, is it obvious for everyone that CRITICAL is more severe than ERROR?

If this needs to be end user-proof, I would reduce the number of levels to three. Four if need be.

Without documentation, I personally would be unable to tell for sure which is more grave: ERROR, FAILURE, or CRITICAL. FATAL I would be able to tell apart but only because I'm a programmer!

Suggestion:

• OK
• WARNING
• ERROR

plus maybe

• CRITICAL ERROR

If I was going to dumb it down and make if obvious to everyone I would only use three levels:

OK
WARNING
ERROR

OK is all good, warning doesn't necessarily need immediate attention, error must be looked at right now.

You could of course keep the extra levels in the background and show them in a more advanced mode or wherever they will better understood.

I agree with the OK, WARNING, ERROR flags that Pekka and Steve Claridge provided.

If you really "want it to be very obvious for even a casual user", bold the ERROR messages. In addition, make the OK messages green, the WARNING messages yellow, and the ERROR messages red. These colors correspond to United States traffic signals.

The colors should be a system option, because other countries use different sets of colors for traffic signals.

The bolding and colors are in addition to the OK, WARNING, ERROR flags, not a replacement for the flags.