The Refvars readback information on the bot located in the focus-eye set by .focuseye which by default is .eye5. If there is no bot in the focus-eye refvars are set by touch. Basically based on the information received the bot will be programed to behave in specific ways. If it is a conspecific the bot will normally not shoot and will turn away.
cond *.refeye *.myeye != *.eye5 37 > start -1 .shoot store stop
The two main groups of ref's are those that tell numbers of DNA commands within a bot and those that tell characteristics of a bot.
Refeye for instance tells the number of .eyeX commands within a bot. Refpoison will readback the amount of poison a bot has.
A slight issue with over relying on these is that the commands that appear to be used by the dna, may not in fact be in actual use.
cond start .tie .shoot .aimdx .eye5 add add add add dup sub stop end
This would give the bot the appearance of being able to turn, tie, shoot, and see but in fact the values are being used as pure numbers to have no actual affect.
The exact opposite can also be done, deliberately hiding a bots abilities by encoding them as numbers, making a deadly bot seem harmless.