12. A computer-assisted method of exposing transforms applicable to a document family, including: maintaining a document family registry data structure, including for a particular document family document family versions; transforms including program instructions that transform data between document family versions; responding to requests that identify first and second document family versions by providing one or more sequences of transforms or references to transforms to be executed remotely, that transform the data from the first document family version to the second document family version.
12. A computer-assisted method of exposing transforms applicable to a document family, including: maintaining a document family registry data structure, including for a particular document family document family versions; transforms including program instructions that transform data between document family versions; responding to requests that identify first and second document family versions by providing one or more sequences of transforms or references to transforms to be executed remotely, that transform the data from the first document family version to the second document family version. 20. The method of claim 12 , wherein: maintaining the document family registry data structure further includes maintaining special rules for transforms to be applied corresponding to one or more participants in a document exchange; and responding further includes referring to private transforms, maintained securely within the document family registry data structure.