The Mary Sue Protocol is a common protocol for World of Warcraft roleplaying add-ons to communicate with each others in order to send user data such as roleplay profiles.
It is a simple challenge/response protocol, where a client send request to another client to pull data. It includes versioning for individual fields, group requests for tooltip data, and a throttle to avoid excessive communication.
The orignal LibMSP is hosted on its author, Etarna,'s website as a ZIP file. I found this very limiting and wanted a way for any user of the LibMSP library to participate in its improvement. I strongly encourage any developer of an RP add-on that uses the LibMSP to come here and participate, offer help and suggestions to improve the library, participate in the documentation, in hope that this repository will replace the static website as the source for the LibMSP library.
The original documentation from Etarna for LibMSP is available on this repository wiki
You can also check Townlong Yak's Globe tool to see which add-ons are writting or reading the LibMSP's global variable https://www.townlong-yak.com/globe/wut/#q:msp