-- some of the types

Service-Requirements ::=
    SEQUENCE {
	version[0]
	    Versions,

	credentials[1]
	    Credentials OPTIONAL,

	extensions[2]
	    SET OF Extension OPTIONAL
    }

Versions ::=
    BIT STRING { version-1 (0) }
    
Service-Diagnostic ::=
    SET {
	versions[0]
	    SEQUENCE OF Versions OPTIONAL,

	reason
	    Diagnostic-Reason
    }

...