Where is validation done and how much is necessary?
There is a scale of choices with respect to the validation of XML documents. On the rigid spectrum one uses all possible features of a DTD to do validation, on the other side, one gives up on DTDs because they are so weak anyway, and does all validation in the application. FpML takes a middle ground. As much validation with DTD’s is done as possible without having that force unnecessary burden on the expressibility or consistency. Schemata languages will pick up some of the remaining validation issues, (e.g. to check types and enumerations, which FpML does not represent as attributes), but there is a requirement for doing validation in the application or a validation services (which could then sign the information component, so no repeat validation would be necessary). The main areas of validation that fall in that category are referential integrity of named and referred elements and the instrument specific appropriate values of elements. The latter needs to be described with the eleme
