How to Read a Network Jack
You need 2 pieces of information: the faceplate identification AND the port number.
The faceplate identification is printed as 3 numbers separated by dashes.
(For example 010-1-008)
The Port number is a four-digit number printed next to each port on the faceplate. (For example 0018)
Put the two parts together and you get: 010-1-008 0018
In the illustration, 010-1-008 0018 is the jack # for the wire plugged into the left side.
(In some cases, another label will indicate which of the ports is wired for a computer, as it is in the illustration here, which says "Data - 0018")
Each Faceplate has different numbers, of course, but that is the gist of jack numbers.