I hope this message finds you well.

I am currently working with the MariaDB vector functionality and am particularly interested in the modified HNSW (MHNSW) algorithm. Specifically, I would like to inquire about the meaning and usage of the parameter "M" in MHNSW, as well as how it compares to other HNSW implementations, such as pgvector. （https://mariadb.com/kb/en/vector-system-variables/）

Typically, HNSW has two key construction parameters: "M" and "efconstruction." However, I noticed that in MHNSW, there doesn't seem to be an "efc" parameter. This has led me to wonder if the "M" parameter in MHNSW has a different meaning or purpose compared to the traditional HNSW "M." 

Could you kindly clarify the role of the "M" parameter in the modified HNSW algorithm, and how it differs from or is similar to other implementations like pgvector?

Thank you for your time and assistance. I look forward to your response.

Best regards！