diff --git a/doc/blkparse.1 b/doc/blkparse.1
index 4c26baf..93aa449 100644
--- a/doc/blkparse.1
+++ b/doc/blkparse.1
@@ -435,10 +435,41 @@
 
 .SH "RWBS DESCRIPTION"
 
-This is a small string containing at least one character ('R' for read, 'W'
-for write, or 'D' for block discard operation), and optionally either
-a 'B' (for barrier operations) or 'S' (for synchronous operations).
+This is a small string containing characters in the following order:
 
+.IP F
+Flush
+
+.IP R
+Read
+
+.IP W
+Write
+
+.IP D
+Discard
+
+.IP B
+Barrier
+
+.IP N
+Other operation
+
+.IP F
+Force Unit Access (FUA)
+
+.IP A
+Readahead
+
+.IP S
+Synchronous
+
+.IP M
+Meta
+
+.PP
+One of 'R', 'W', 'D', or 'N' is always present. The other characters are
+optional. Note that 'F' has two meanings, depending on its position.
 
 .SH "DEFAULT OUTPUT"
 
diff --git a/doc/blktrace.tex b/doc/blktrace.tex
index 836ac4a..d747de7 100644
--- a/doc/blktrace.tex
+++ b/doc/blktrace.tex
@@ -653,9 +653,24 @@
 \end{tabular}
 
 \subsubsection{\label{sec:act-table}RWBS Description}
-This is a small string containing at least one character ('R' for read,
-'W' for write, or 'D' for block discard operation), and optionally either
-a 'B' (for barrier operations) or 'S' (for synchronous operations).
+This is a small string containing characters in the following order:
+
+\begin{tabular}{|l|l|}\hline
+Character & Description \\ \hline\hline
+F & Flush \\ \hline
+R & Read \\ \hline
+W & Write \\ \hline
+D & Discard \\ \hline
+B & Barrier \\ \hline
+N & Other operation \\ \hline
+F & Force Unit Access (FUA) \\ \hline
+A & Readahead \\ \hline
+S & Synchronous \\ \hline
+M & Meta \\ \hline
+\end{tabular}
+
+One of 'R', 'W', 'D', or 'N' is always present. The other characters are
+optional. Note that 'F' has two meanings, depending on its position.
 
 \subsubsection{\label{sec:default-output}Default output}