Reference pin marking clarification

I’m experimenting with my Wio terminal Serial1 port on pins 8 and 10 on the reference diagram. Without any explanation, I am guessing the blue pins with BCM designations are the pins on raspberry pi and the other colors are functions of Wio terminal. On pin 8 marked as BCM14 and TXD, I can get the TXD output so I know this is the TXD. I was printing ASCII table with an arduino sample code (great job arduino!). I guess I should interpret the markings with a Wio terminal-centric view point. Correct? Maybe RPI people should have adopted an RPI-centric view point and mark BCM14 as RXD. :slight_smile:
How are the pin coloring work? Should have a legend if they use color.