[Params] images static or not?

In section 3.7.1 you mention that <image> can reference 'replacement
content'.  In other documents I've seen it expressed that when SVG is
referenced in an image context (html:img or svg:image) it should be
treated like a static image without DOM.

If the UA has to update its rendering when parameters change, do these
conflict?

Maybe my memory is incorrect on this.  Do you need verbage to the
effect that images cannot change after initial rendering?

Regards,
Jeff Schiller