SVG Layers : Help needed

hello ,

I am a java programmer , new to SVG . we are developing a java application , which is used for developing themes for mobile devices. We uses svg files extensively , as images and backgrounds. User can edit the svg files using Thirdparty svg editors like Inkscape, Adobe Illustaror etc .
 
Now we are trying to implement a  new functionality, which is helpful for theme designers.Instead of editing svg files individually , we thought of collecting multiple SVG files and generate a single SVG file that contains a background layer and one layer for each individual SVG file. The layers shall be named so that when copying back to the tool,each SVG can be identified and applied to the corresponding elements. This will ease the job of designer , so he can do the necessary batch processing in the layers.
 
Now the problem is how can i structure the svg document in such a way that each layer can accomodate one svg document , each has its on viewBox attribute specified ?
Does SVG have any builtin support for layers other than <g> tag ?
 
Any help wi will be appreciated . Thanks in advance