-.Qq \-
-for standard input. The default is standard input.
-.It Fl v
-Print messages (output depends on filter).
-.It Fl W
-Print warnings (output depends on filter).
+.Dq \-
+for stdin.
+.El
+.Pp
+By default,
+.Nm
+reads from stdin and writes to stdout.
+.Pp
+.Ex -std mdocml
+.\"
+.Ss Noop Filter
+The default noop
+.Dq validating
+filter simply validates its input; it produces no output beyond error
+and warning messages.
+.\"
+.Ss XML Filter
+The XML filter, specified by
+.Fl f Ar xml ,
+produces correctly-formatted XML output. This filter has no additional
+arguments.
+.Pp
+The XML filter creates an XML document where element names are their respective
+roff macro names. Each element name has an associated
+namespace, which is one of
+.Dq block ,
+.Dq head ,
+.Dq body ,
+or
+.Dq inline ,
+corresponding to the display mode of a node. The document root is
+always the
+.Dq mdoc
+element, in the default namespace; the
+.Dq head
+namespace is for block headers (such as
+.Sq .Ss
+and
+.Sq .Sh ) ;
+the
+.Dq body
+namespace is for block bodies; and the
+.Dq inline
+namespace is for in-line elements (such as
+.Sq .Em ) .
+.\"
+.Ss HTML Filter
+The HTML filter, specified by
+.Fl f Ar html ,
+accepts the following filter-specific arguments:
+.Bl -tag -width "\-c css"
+.It Fl c Ar css
+The CSS file location, which defaults to
+.Ar mdocml.css .
+.It Fl e
+Whether to embed the CSS file into the HTML prologue.