The one quality shop I know of how they work does it so :
They're intrested in my drawing, but PDF is OK since it's only for reference on dims. They're intrested in the 3D-model in any solid transfer format they can read. They're not intrested in the flat pattern, since they only trust their own parameters.
What they do is import the 3D model in their fabrication sheetmetal program (name I don't remember, but it is fabrication centered rather than design centered. Next step is designate all the bends and attribute the parameters they know will be used. When all bends are processed the program unfolds, operator checks and part is ready to proceed to preproduction.
How the part gets produced and what bends come in what order on what press is entirely their responsibility based on the endresult needed and their experience. If intermediate steps are necessary they will decide.
So basically they need to know what the product is in its final stage and nothing else.
I have learned that there is an add on package called Progressive Die Extension that will allowsheetmetal tooling venders to flatten sheetmetal forms. Instead of creating simply a flat pattern las Pro/SHEETMETAL software andrespectivedesigners do, this module upon flattening creates individual bends as separate operations.(which allows avender topartially strike.I believe it will even let a vender reorder the operations amongh many other things.
For the IGES stuff I think the best solution thus far is to either fill in the places where the sheetmetal form vears from a nominal wall thickness or remodel the sheetmetal form from the part of the form that does not convert.