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.