Index: appendix/wps_tags.tex
===================================================================
--- appendix/wps_tags.tex	(revision 20068)
+++ appendix/wps_tags.tex	(working copy)
@@ -1,5 +1,106 @@
 % $Id$ %
 \chapter{\label{ref:wps_tags}WPS Tags}
+
+\optv{lcd_bitmap}{
+\section{Viewports}
+By default, a WPS fills the whole screen, and is split in as many lines will
+fit with the chosen font. Using viewports, you can define rectangular areas of
+the screen, in which to display information. All lines before the first
+viewport definition will be shown in the default viewport, which covers the
+entire screen. All lines following a viewport definition and up to the next
+definition or end of file will will be drawn in that viewport.
+
+\note{
+  \begin{itemize}
+    \item  If a viewport has been defined, it is not possible to display text
+           on the default viewport. Use it for pictures only.
+    \item  Viewports cannot overlap eachother transparently. Viewports will be
+           drawn on top of earlier viewports.
+    \item  The maximum number of viewports is 24.
+  \end{itemize}
+}
+
+\begin{table}
+  \begin{tagmap}{}{}
+    \config{\%V{\textbar}x{\textbar}y{\textbar}[w]{\textbar}[h]{\textbar}\opt{lcd_non-mono}{[font]{\textbar}[fg]{\textbar}[bg]{\textbar}}}
+     & Define a viewport\\
+     & \config{x}: x coordinate of top-left corner\\
+     & \config{y}: y coordinate\\
+     & \config{w}: Width of the viewport. Defaults to fill the screen to the right.\\
+     & \config{h}: Height. Defaults to fill the screen downards.\\
+     & \config{font}: Which font to use. 0 means builtin system font. 1 means the user-selected font.\\
+\opt{lcd_color}{
+     & \config{fg}: Foreground colour for the viewport. RGB888 Hex triplet (e.g. FF0000 means red).\\
+     & \config{bg}: Background colour.\\
+}
+\nopt{lcd_color}{
+\opt{lcd_non-mono}{
+     & \config{fg}: Foreground shade for the viewport. A number between 0 (black) and 3 (white).\\
+     & \config{bg}: Background shade.\\
+}
+\nopt{lcd_non-mono}{ & \fixme{This line should be removed, but that produces
+syntax errors.}\\ }
+}
+  \end{tagmap}
+\end{table}
+
+\begin{example}
+    \%V|20|10|30|15|-|-|-|
+    \%sExample test string
+\end{example}
+
+\nopt{lcd_non-mono}{
+  \fixme{
+    The above example uses the syntax for non-mono displays due to issues
+    with {\textbackslash}opt and the example environment.
+  }
+}
+
+This example WPS will set up a small viewport 30x15 pixels, at x=20,y=10
+containing the text ``Example test string'' using the user font and default
+colours. The text will scroll to stay inside the defined area.
+
+\subsection{Conditional Viewports}
+Just as with regular viewports, conditional viewports define an area of the
+screen where drawing happens. However, conditional viewports consist of two
+parts: A viewport definition, very similar to the regular one, and a display
+tag that switches display of this particular viewport on.
+
+\begin{table}
+  \begin{tagmap}{}{}
+    \config{\%Vl{\textbar}n{\textbar}\ldots{}{\textbar}}
+     & Preload a viewport for displaying later with the \config{\%Vd} tag.\\
+     & \config{n}: A single lower-case identifier (a-z)\\
+     & \config{\ldots{}}: The rest of the values are the same as the regular
+       viewports tag.\\
+    \config{\%Vdn}
+    & Display a preloaded viewport\\
+    & \config{n}: The identifier as set in the \config{\%Vl} tag.\\
+  \end{tagmap}
+\end{table}
+
+\begin{example}
+    \%Vl|a|10|15|40|20|-|FF0000|-|
+    Repeat disabled
+    \%Vl|b|10|45|40|20|-|00FF00|-|
+    Repeat enabled
+    \%?mm<\%Vda|\%Vdb>
+\end{example}
+
+\nopt{lcd_color}{
+  \fixme{
+    This example uses the syntax for colour screens due to issues with
+    {\textbackslash}opt and the example environment
+  }
+}
+
+This example defines two viewports with the size 40x20 pixels. The first one is
+at x=10,y=15 and has a red foreground colour, with the text ``Repeat
+disabled''. The other is at x=10,y=45 with the text ``Repeat enabled'' in green
+text. The last line displays either one or the other, depending on the repeat
+setting.
+}
+
 \section{Status Bar}
 \begin{table}
 \begin{tagmap}{}{}