The FIFe Easy Mind System for Identifying Cats
The FIFe's Easy Mind System (EMS) simplifies and replaces the combination of letters and numbers used to identify cats. In that system, identification codes were not always uniform across breeds. In the EMS they are. A black cat, for example, is always identified by the small letter "n" no matter what its breed. The first part of the EMS code, written in capital (uppercase) letters, denotes the breed.

Recognized Colour of Coat            
n = black ("n" comes from the French noir, meaning black)
a = blue, looks like grey and varies between dark and light, it's a dilution of black
d = red, all reds cats have a tabby pattern.    
e = cream, looks like a mix between white and red, it's a dilution of red
f = black tortie, a mix of red and black
g = blue tortie, a mix of blue and crème
s = silver or smoke, in case of a tabby pattern (agouti) it's called silver, if there's no tabby pattern (non-agouti) it's called smoke
w = white
x = any unrecognized colour (for example until 2005 the amber varieties were placed in this group)

nt = amber, applicable only to the Norwegian Forest Cat. Amber is only recognized for black within the existing colour varieties of the Norwegian Forest Cat.
at = light amber, applicable only to the Norwegian Forest Cat. Light amber is only recognized for blue within the existing colour varieties of the Norwegian Forest Cat.

Cats With White
01 = 'van', the biggest part of the body is white, only the head and tail have coloured spots
02 = harlequin, ¾ white and ¼ coloured
03 = bicolour, ½ white and ½ coloured
09 = unspecified amount of white

Recognized Patterns
21 = agouti = unspecified tabby pattern (used by the Van or Harlequin varieties where only small areas of the body display the pattern)
22 = blotched tabby pattern, also known as classic tabby
23 = mackerel tabby pattern
24 = spotted tabby pattern
25 = ticked tabby pattern
 

blotched (classic) tabby	mackerel tabby	spotted tabby	ticked tabby

Recognized Eye colour
61 = blue
62 = yellow, golden or orange
63 = odd eyed, one eye is blue the other eye is green, yellow or orange
64 = green