# What does the red symbol mean here?

I found this symbol on the schematics of an FPGA board. AIN stand for Analog input.

If you didn't cut off the picture, you'd see the wires are labelled AIN15_P, AIN15_N, AIN16_P, AIN16_N. The red symbol tells Altium that these signals (each matching P and N pair) should be considered a differential pair.