37. A computer readable medium for use in validating an eXtensible Markup Language (XML) message, said computer readable medium containing computer-executable instructions which, when performed by a processor in a computing device, cause the computing device to: from a custom XML schema based message model having at least one logical model extension, generate an XML schema fragment for use in validating said XML message at a node which lacks said custom XML schema based message model, wherein said custom XML schema based message model comprises a logical model of said XML message that complies with a standard XML schema, and wherein said custom XML schema based message model comprises a physical model that customizes said message using a logical model extension that is unsupported by said standard XML schema, wherein said custom XML schema based message model has an original group representing at least a portion of said XML message, said logical model extension being associated with said original group, and wherein said original group has an original sequence declaration containing a set of original subordinate entities, and wherein generating said XML schema fragment comprises: generating a new group; generating a sequence declaration within said new group, said sequence declaration having a minimum occurrence attribute with a value equivalent to a total number of said original subordinate entities in said set; and generating a choice declaration within said sequence declaration, said choice declaration containing said set of original subordinate entities.
45. The computer readable medium of claim 37 , wherein generating said XML schema fragment comprises: generating a new group; generating a sequence declaration within said new group; and generating an “any” element declaration within said sequence declaration, said “any” element declaration having a process content attribute specifying lax validation, a minimum occurrence attribute with a value of zero, and a maximum occurrence attribute with a value of “unbounded”.