fix clarification

Author: vladak

file-api.tex

@@ -730,11 +730,10 @@
 \item \texttt{F\_GETLK}, \texttt{F\_SETLK}, \texttt{F\_SETLKW} \dots{}
 for file locking
 \end{itemize}
-\item Note that there are two kinds of flags.  Flags associated with the file
-descriptor, having \texttt{FD} in the macro names \texttt{FD\_CLOEXEC},
-and flags associated with the slot in the system file table of opened files,
-having \texttt{FL} in the \texttt{fcntl} command macros
-(i.e. \texttt{F\_GETFL}).  See also the picture on page \pageref{OPENFILETABLES}.
+\item Note the difference between \texttt{fcntl} commands ending with
+\texttt{FD} and \texttt{FL}. While the former deal with a file descriptor, the
+latter deal with a file opening, i.e. particular slot in the system file table
+of opened files. See also the picture on page \pageref{OPENFILETABLES}.
 \item Devices may support reading and writing using \texttt{read} and
 \texttt{write}, and mapping files to memory (\texttt{mmap}, see page
 \pageref{MMAP}), all other operations on devices (e.g. setting parameters,