I know that the GPIO pins available after PiSound loads are documented at Detailed Specs - Pisound Documentation
However, the documentation says that the blue pins are reserved for PiSound and then lists the following as reserved:
|11||BCM 15 (RXD)|
|12||BCM 14 (TXD)|
|13||BCM 2 (SDA)|
|14||BCM 3 (SLC)|
I can understand the SDA and SLC are used and must not be reassigned to something else, but that other applications can continue to use SDA and SLC for I2C communications.
Is the same true for RXD and TXD?
What does the blue filled in circle mean as opposed to the blue circle with no fill in the GPIO usage diagram?