What is the library 'mblibv1'?

I have been trying to load old models from the r2009a and r2008b versions on the 2015 version but I keep getting a "Failed to load library 'mblibv1' referenced by ____" error. This has been happening on multiple Simulink models and I am starting to believe I am missing a package or something. Please help.

Answer 1

[Walter Roberson]

It looks like it is from SimMechanics