diff --git a/usr.bin/top/top.1 b/usr.bin/top/top.1
--- a/usr.bin/top/top.1
+++ b/usr.bin/top/top.1
@@ -373,7 +373,7 @@
 .It Ic z
 Toggle display of the system idle process.
 .El
-.Sh "THE DISPLAY"
+.Sh THE DISPLAY
 The top few lines of the display show general information
 about the state of the system, including
 the last process id assigned to a process (on most systems),
@@ -385,29 +385,37 @@
 and a percentage of time spent in each of the processor states
 (user, nice, system, and idle).
 It also includes information about physical and virtual memory allocation.
-.Pp
-The remainder of the screen displays information about individual
-processes.
-This display is similar in spirit to
-.Xr ps 1
-but it is not exactly the same.
-PID is the process id,
-JID, when displayed, is the
+The remainder of the screen displays contexual information about
+individual processes.
+.Ss CPU Mode
+In cpu mode, the following columns are available:
+.Bl -tag -width "USERNAME"
+.It PID
+Process ID number.
+.It JID
+When displayed, is the
 .Xr jail 8
-ID corresponding to the process,
-USERNAME is the name of the process's owner (if
+ID corresponding to the process.
+.It USERNAME
+Name of the process's owner. If
 .Fl u
-is specified, a UID column will be substituted for USERNAME),
-THR is the thread count, showing the number of threads a process has,
-PRI is the current priority of the process,
-NICE is the
+is specified, a UID column will be substituted for USERNAME.
+.It THR
+Thread count, showing the number of threads a process has.
+.It PRI
+Current priority of the process.
+.It NICE
+Process's
 .Xr nice 1
-amount,
-SIZE is the total size of the process (text, data, and stack),
-RES is the current amount of resident memory,
-SWAP is the approximate amount of swap, if enabled
-(SIZE, RES and SWAP are given in kilobytes),
-STATE is the current state (one of
+amount.
+.It SIZE
+Total size of the process in KiB (text, data, and stack).
+.It RES
+Current amount of resident memory in KiB.
+.It SWAP
+Approximate amount of swap in KiB, if enabled.
+.It STATE
+Current state, one of
 .Dq START ,
 .Dq RUN
 (shown as
@@ -418,19 +426,7 @@
 .Dq ZOMB ,
 .Dq WAIT ,
 .Dq LOCK ,
-or the event on which the process waits),
-C is the processor number on which the process is executing
-(visible only on SMP systems),
-TIME is the number of system and user cpu seconds that the process has used,
-WCPU, when displayed, is the weighted cpu percentage (this is the same
-value that
-.Xr ps 1
-displays as CPU),
-CPU is the raw percentage and is the field that is sorted to determine
-the order of the processes, and
-COMMAND is the name of the command that the process is currently running
-(if the process is swapped out, this column is marked
-.Dq <swapped> ) .
+or the event on which the process waits.
 .Pp
 If a process is in the
 .Dq SLEEP
@@ -441,8 +437,50 @@
 process is waiting.
 Lock names are prefixed with an asterisk
 .Dq *
-while sleep events
-are not.
+while sleep events are not.
+.It C
+Processor number on which the process is executing
+This is visible only on SMP systems.
+.It TIME
+Number of system and user cpu seconds that the process has used.
+.It WCPU
+Weighted cpu percentage.
+This is the same value that
+.Xr ps 1
+displays as CPU.
+.It CPU
+Raw cpu percentage, this is the field that is sorted to determine
+the order of the processes.
+.It COMMAND
+Name of the command that the process is currently running, or
+.Dq <swapped>
+if the process is swapped out.
+.El
+.Ss IO Mode
+In io mode, the following columns are available:
+.Bl -tag -width "USERNAME"
+.It PID
+Process ID number.
+.It USERNAME
+Name of the process's owner.
+If
+.Fl u
+is specified,
+a UID column will be shown instead displaying the user ID number.
+.It VCSW
+Voluntary context switches.
+.It IVCSW
+Involuntary context switches.
+.It READ
+.It WRITE
+.It FAULT
+.It TOTAL
+.It PERCENT
+.It COMMAND
+Name of the command the process is currently running, or
+.Dq <swapped>
+if the process is swapped out.
+.El
 .Sh DESCRIPTION OF MEMORY
 .Bd -literal
 Mem: 61M Active, 86M Inact, 368K Laundry, 22G Wired, 102G Free