libmono-system-identitymodel4.0-cil 5.18.0.240+dfsg-3 (amd64 binary) in ubuntu focal

 Mono is a platform for running and developing applications based on the
 ECMA/ISO Standards. Mono is an open source effort led by Xamarin.
 Mono provides a complete CLR (Common Language Runtime) including compiler and
 runtime, which can produce and execute CIL (Common Intermediate Language)
 bytecode (aka assemblies), and a class library.
 .
 This package contains the System.IdentityModel library which is part of
 the Windows Communication Foundation (WCF) libraries of Mono for CLI 4.0.
 The WFC stack is for building SOA-based applications.
 Its development is in early stages.