Oslo is a code name of Microsoft’s new modeling platform. Modeling is used across a wide range of domains and allows more people to participate in application designs and allows developer to write application at much higher level of abstraction.
“M” is a new programming language and just developed by Microsoft. This language is for building textual domain specific languages and software mode with XAML. Actually “M” is again a code name
You can study following URLs for more information as I got an idea about the same from below URLs:
Reference: Ritesh Shah