In the schematic screenshot below (from example 1 here), there is a little red symbol on some of the lines - e.g., where the big red arrow is pointing:

illustration of mysterious schematic symbol

Here’s another online schematic where the same symbol is used.

I can't figure out what the red symbol means. My best guess is that its some EDA program’s net class indicator, because they seem to come in pairs, but I’m really not sure. Does anyone know if this red symbol means anything?

(Tagged usb because I've only seen this in USB-related schematics, but that might just be a function of what I tend to browse for.)


1 Answer 1


It indicates that the signal is part of a differential pair.

  • 1
    \$\begingroup\$ This makes complete sense and explains why I keep seeing it in USB circuits. Thank you. \$\endgroup\$
    – jemalloc
    Commented Jan 6, 2023 at 16:06
  • 3
    \$\begingroup\$ Worth pointing out that it is depicting two waveforms with opposite polarity, similar to what differential signal looks like usually. \$\endgroup\$
    – Eugene Sh.
    Commented Jan 6, 2023 at 16:24

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