The <Library> element specifies an extension library to load at runtime.
Extensions are dynamic/shared libraries (DLLs) with special exported functions to allow them to be loaded by the SP. Extensions can be loaded in-process (in the web server), out-of-process (in shibd), or both, but are normally designed to used in one context or the other.
Specifies the path to the library to load.
If true, a failure to load the library will fatally terminate the overall initialization of the relevant part of the SP.
The schema permits arbitrary child elements and attributes to be present, allowing extension libraries to include their own configuration material if they need to.