Basic question - PHP usage of SVG files

PHP list, I have some images that are in SVG format. What I want to do with them is manipulate them by resizing and overlaying one on top of the other. I do this frequently with PNG images, and I could first convert these images to PNG before manipulating them in PHP. However, I'd like to preserve line quality by keeping them as SVG until the last moment. I can't see on the online documentation if SVG is supported and if it requires different commands than raster image formats. What is the support for SVG in PHP, and where is the online documentation for it? Thank you for your help. -- Dave M G