The ISO standard for HDLC procedures (ISO 4335) includes the following definitions:

(1) an REJ condition is considered cleared upon the receipt of an incoming I-frame with an N(S) equal to the N(R) of the outgoing REJ frame; and (2) a SREJ condition is considered cleared upon the receipt of an I-frame with an N(S) equal to the N(R) of the SREJ frame. The standard includes rules concerning the relationship between REJ and SREJ frames. These rules indicate what is allowable (in terms of transmitting REJ and SREJ frames) if an REJ condition has not yet been cleared and what is allowable if an SREJ condition has not yet been cleared. Deduce the rules and justify your answer.