I would say PDFs are actually reasonably consistent though. Weird things happen on occasion, but I've certainly had more success than with SVGs.
They are reasonably consistent because there is a de-facto reference implementation (Adobe Acrobat) which, if your implementation does not match exactly, users will think your implementation is broken.
There isn't such an implementation for SVG.
They are reasonably consistent because there is a de-facto reference implementation (Adobe Acrobat) which, if your implementation does not match exactly, users will think your implementation is broken.
There isn't such an implementation for SVG.