Alcance
                            ISO 18443:2016 Practice defines extensions to the SLE API in terms of:a)    the RCF-specific functionality provided by API components;b)    the RCF-specific interfaces provided by API components; andc)    the externally visible behavior associated with the RCF interfaces exported by the components.It does not specify:a)    individual implementations or products;b)    the internal design of the components; andc)    the technology used for communications.ISO 18443:2016 defines only interfaces and behavior that must be provided by implementations supporting the Return Channel Frames service in addition to the specification in reference [3].