The POSIX standard, and the Linux documentation, states that when multiple real time signals of different types are pending delivery to a process (that is the process is blocking them); then, at some point, when the process's signal mask is unblocked (thereby allowing the signals to be delivered), the signals are indeed delivered in priority order: lowest signal number to highest signal number.
Let's test this: we write a program that traps and blocks upon the delivery of three real time signals: {SIGRTMAX-5, SIGRTMAX, SIGRTMIN+5}. (Have a look at the output of kill -l; their integer values are {59, 64, 39} respectively.)
Importantly, our program will, at the time of sigaction(2), use the sigfillset(3) convenience ...
