https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83057
--- Comment #2 from urbanjost at comcast dot net --- A long-standing convention when referencing procedures anprd commands, especially on Unix platforms is to suffix them with (category[group]) to distinguish them from English words and to identify if talking about a procedure or a command. "(3f)" just means a callalable function or procedure, f typically means Fortran, "c" for the C programming language, "X11" for X11 Windows routines and so on. This helps to clarify such things as sleep, sleep(1), and sleep(3c) --- respectively meaning "to slumber", the GNU/Linux or Unix command sleep, and and the C routine sleep.
