-.IP "\fBvlog/set\fR \fImodule\fR[\fB:\fIfacility\fR[\fB:\fIlevel\fR]]"
-Sets the logging level for \fImodule\fR in \fIfacility\fR to
-\fIlevel\fR. The \fImodule\fR may be any valid module name (as
-displayed by the \fB--list\fR option) or the special name \fBANY\fR to
-set the logging levels for all modules. The \fIfacility\fR may be
-\fBsyslog\fR or \fBconsole\fR to set the levels for logging to the
-system log or to the console, respectively, or \fBANY\fR to set the
-logging levels for both facilities. If it is omitted,
-\fIfacility\fR defaults to \fBANY\fR. The \fIlevel\fR must be one of
-\fBemer\fR, \fBerr\fR, \fBwarn\fR, \fBinfo\fR, or \fBdbg\fR, designating the
-minimum severity of a message for it to be logged. If it is omitted,
-\fIlevel\fR defaults to \fBdbg\fR.
+.IP "\fBvlog/set\fR [\fIspec\fR]"
+Sets logging levels. Without any \fIspec\fR, sets the log level for
+every module and facility to \fBdbg\fR. Otherwise, \fIspec\fR is a
+list of words separated by spaces or commas or colons, up to one from
+each category below:
+.
+.RS
+.IP \(bu
+A valid module name, as displayed by the \fBvlog/list\fR command on
+\fBovs\-appctl\fR(8), limits the log level change to the specified
+module.
+.
+.IP \(bu
+\fBsyslog\fR, \fBconsole\fR, or \fBfile\fR, to limit the log level
+change to only to the system log, to the console, or to a file,
+respectively.
+.IP
+On Windows platform, \fBsyslog\fR is accepted as a word and
+is only useful if the \fItarget\fR was started with the
+\fB\-\-syslog\-target\fR option (the word has no effect otherwise).
+.
+.IP \(bu
+\fBoff\fR, \fBemer\fR, \fBerr\fR, \fBwarn\fR, \fBinfo\fR, or
+\fBdbg\fR, to control the log level. Messages of the given severity
+or higher will be logged, and messages of lower severity will be
+filtered out. \fBoff\fR filters out all messages.
+.RE
+.
+.IP
+Case is not significant within \fIspec\fR.
+.IP
+Regardless of the log levels set for \fBfile\fR, logging to a file
+will not take place unless the target application was invoked with the
+\fB\-\-log\-file\fR option.
+.IP
+For compatibility with older versions of OVS, \fBany\fR is accepted as
+a word but has no effect.