old-school Hungarian Notation “mz” prefix

Question

Every so often, I need to dig into older APIs, and I keep running across functions with an "mz" prefix for API calls. (Example, functions like mzListDocuments()

I'm just curious what this "mz" stands for in this context. I'm aware of old Hungarian notation ideas like "m_" for member objects, etc, but Google is failing me on the "mz" prefix.

I initially assumed it was an internal company standard from the software vendors, but I've seen it from multiple vendors, so now I'm wondering if it was once very common, or even a recommended standard.

I can't remember all of the vendors, but currently I'm seeing this with a document scanning system's API. The API is older, it used DCOM, and the functions all return integer data types. The software was written in c++.

The APIs are meant to be called from VBScript, VB, or .NET. The mz prefix is in front of all function names, and constants are all prefixed with "MZ_" (Examples "MZ_FORMATPDF" and "MZ_FORMATMSWORD").

Based on the context all I can tell is that the "mz" prefix means" we're using API members".

This could be meaningless, and it's not like I need to know the answer to this in order to be productive. This is more a curiosity question than anything else.