zooming

hi,
i am new to svg.these days i am developing a small gis system using svg.
in here i want to zoom a given area.
that means user can select certain area of the map (rectangle) using mouse and get more detailed view of that.
the zooming shold be like this.
initially the map shows only the area boundries.
in the second step it shold show the roads with previous content.
likewise each zooming step the data should be increased.
i tried this using java script.
but there are lot of problems.
if you can pls help me.
thank you.
regards,
kelum.

For zoom on rectangle draw by user see
http://pilat.free.fr/tutorial2/zoom.svg
For show new data, you can load all data and play with visibility property.
You can also load data on zoom using getURL, parseXML and appendChild to your DOM.

With RCC in ASV6 beta, you can add property to elements and they will be draw only with some degree for zoom
See example at
http://pilat.free.fr/asv6/rcc/level.htm
( need ASV6 beta ... )

Michel