Attached is a screen shot of the pictograph that ExpressPCB uses to represent T 1.75 LED's. In their layout tips, they say that a square pad should be used to represent the positive lead in a polarized component. I am confused by what seems to be a contradiction.

The flat side of an LED is (usually) the cathode, which is the negative side, right? And yet they use a square pad to represent the cathode. Or am I wrong as usual?

 

It really doesn't matter. Put it on the anode side if you wish. Typically I use a square pad to indicate position 1 of a header/connector,etc...

 

That is the convention for LED's. Just recall that the LED cathode is the short lead.

 

Actually, that's the convention for diodes in general. For parts with numbered pins, the square pad is used for pin 1.
/mike