In order to link a github user to the same user in the PlanB Network platform, we have decided to defined a 2-words username as an unified UID.
It is an identifier made out of 2 words from bip39 dictionary for identifying contributors or professors like another-satoshi
You need a BIP39 ID if you are a professor or a contributor (like a proofreader, a translator or a content creator) of PBN.
These words are "randomly" picked by PBN team from the BIP39 wordlists.