The purpose of the Common Language Infrastructure (CLI) is to provide a language-neutral platform for application development and execution, including functions for exception handling, garbage collection, security, and interoperability. By implementing the core aspects of .NET Framework within the scope of the CLI, this functionality will not be tied to a single language but will be available across the many languages supported by the framework. Microsoft's implementation of the CLI is called the Common Language Runtime, or CLR. The CIL code is housed in CLI assemblies. As mandated by the specification, assemblies are stored in the Portable Executable (PE) format, common on the Windows platform for all DLL and EXE files. The assembly consists of one or more files, one of which must contain the manifest, which has the metadata for the assembly. The complete name of an assembly (not to be confused with the filename on disk) contains its simple text name, version number, culture, and public key token. Assemblies are considered equivalent if they share the same complete name, excluding the revision of the version number. A private key can also be used by the creator of the assembly for strong naming. The public key token identifies which public key an assembly is signed with. Only the creator of the keypair (typically .NET developer signing the assembly) can sign assemblies that have the same strong name as a previous version assembly, since the creator is in possession of the private key. Strong naming is required to add assemblies to the Global Assembly Cache.