In modulo arithmetic, adding or subtracting the base does not change the value. Thus, 12 modulo 9 is the same as 3 modulo 9. Thus, for example, "my iPhone is working great modulo the Wifi connection" implies that if you can subtract the base ("the Wifi connection") you can transform a description of the current state of my iPhone into "working great".

(For your amusement: modulo in the Jargon File. Epsilon is there too.)

Edit: Actually, in this case, you would have to add the base, because my Wifi isn't working, but the statement remains the same.