This is lower priority than many things, but a while back we tried to create a DFDL schema for TIFF and failed.
DFDL features for base+offset location of elements never were designed. They were dropped in the haste to get DFDL v1.0 finished. But I happened to ask Dave Sugar of the Tresys CADRE team whether the CADRE engine (a binary data format description - for wire-speed applications) could do TIFF? Turns out some work was done on this, and I was able to look at the format specification for TIFF (a prototype thereof for CADRE). So the features for DFDL to suppport base + offset locations don't seem too daunting. I created a wiki page to capture the design ideas here. There's more work to do on this. We really should write the DFDL schema for TIFF using these features to be sure we're happy with it. Thus far I've not taken the time to do that. I've just recorded the basic ideas. https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=74687382