Is there a good reason not to name most digital signals in the flavor of COPI/CIPO (MOSI/MISO)
It can be tricky. It’s reminiscent of the RS-232 headaches of DTE vs. DCE and crossover vs. non-crossover cables.
Basically you have to check. Read the specifications carefully. Draw a diagram if you have to.
For example, TX and RX for the PCIe slot are from the host point of view. The M.2 NVMe spec on the other hand, they’re from the card’s point of view.
SATA is even worse. The pairs are labeled ‘A’ and B’. And SATA often coexists with NVMe on cabling and drive connectors.