Explanation
A model library is a package that contains reusable model elements that can be imported into other models. A model library can add common concepts to a SysML model, such as units, quantities, value types, etc. These concepts can be used to define properties and parameters of blocks and constraints in a consistent and standardized way. References:
https://www.omg.org/ocsmp/ocsmp-adv-exam.htmhttps://www.omg.org/spec/SysML/1.6/PDF