Is there an official XML Schema (xsd) for EDI X12 856?

I am still fairly new to EDI, and learning it on a new job. We are using BizTalk for our EDI solution, and are converting the incoming EDI file into XML. I was having problems with a file from a new vendor, and at first thought the file might be incorrect. I have since learned that the file is correct, but our current XML schema is home grown, and would basically need to be tailored to accept this 856. I guess some of the data being passed in is more then what our usual vendors pass to us (still valid according to EDI X12 856 though).

While I could do this, it seems like the real answer is getting an xsd file for the actual EDI spec. It seems like with such a standardized format it should already exist. Does anyone know if such a thing is available?

UPDATE: It turns out there is a built in EDI mapping capability that is done in the pipeline through the "EDI Disassembler" component. This converts to a standardized BizTalk EDI schema and is working correctly. Apparently our code then converts that XML into our own XML schema. There is definitely room to improve, but I think the information on schema standards is what I am looking for at this point.

I don't quite understand the question. I'm assuming BizTalk has EDI mapping capabilities, and that you've used it to map elements of the EDI format to your XML tags. If they're sending a segment that's not in your schema, doesn't the mapper ignore it?

Assuming the sender is using XML EDI rather than binary EDI, there are schemas available. http://www.x12.org/ has a link to them (requires JavaScript), but you have to register. I'm used to paying for everything EDI-related (documentation, translation, testing, etc.) so you may have to purchase them.

Here's an additional link I found to a commercial product: stylusstudio

EDIT: Direct link: http://xml.x12.org/