On a refrigerator schematic I am studying. There is a term i am not familiar with. It is called Tab. To test a voltage the instructions say test from J7-9 to Tab 1. The J79 is neutral on the board and Tab1 goes into the power board. It is a black wire. So I am assuming Tab means black something. Either the wire or the connection at the board. It is on the high voltage side which is 120 volts. Are there any good reading material on schematics, testing and power boards. Can't seem to find any information on this subject. Of course I could post a sample of the schematic I am looking at if need be. But someone may know what these terms mean. I assume J stands for junction, not sure and Tab, I have no clue.