Does "Extern function" imply dynamic loading?

[rakhimov]

Built-Ins:Extern functions:

The Model Exchange Format should provide a mean to call extern
functions. This makes it extensible and allows linking the PSA assessment tools
with complex tools...

From the specification, I am assuming
that the Extern functions have a similar nature to C "extern" functions
to enable calls to functions from other libraries;
however, it is not clear how to specify the source tool/library.
In my understanding, this feature requires the name of a library with the function
to be loaded dynamically.
In case of dynamic loading,
what should the expected function type be?
(double(double, double, ...) or float(float, float, ...) or some other types)