BEP process: source and target data requirement?

[arokem]

Following up on a conversation with @neurolabusc at the steering group meeting just now and related to https://github.com/bids-standard/bids-specification/issues/1350. This page: https://github.com/bids-standard/bids-website/blob/gh-pages/_pages/bep_guide.md needs be edited to better describe the need for complete source and target datasets -- across different vendors -- that describe how conversion should occur. This could also describe how interaction with tool-builders, with instrument vendors, and with the dicom working group should proceed, so that the implementation of conversion into standard-compatible data can be consistent with the implementation, and with the existing dicom standard, where such exists.