So my best guess would be that pin0 is a reference to GPIO0 and pin1 is a reference to GPIO1 I cannot be certain but I just sat down to think about writing code to handle the NodeMCU and this is the one thing that kind of slipped my mind if I am ever going to get this to work I need to know what GPIO is being referenced by what pin using the Basic firmware.
I could most likely figure it out cheaply with a meter metering the pin and ground but if the info is already known it would be nice to see some public documentation on this one.
View the attachment as it currently stands for LUA.
Where I buy my ESP8266 boards from... (Banggood)