Yes, XSDs essentially, and namespaces. I once wrote a dynamic factory parser that matched an unknown XSD document to an unknown XML data structure that checked if it passed the contract or not. I hated writing xml, xsds, xlsts, and brxml; basically the whole thing. The company I wrote it for, fired me right afterwards because they thought they got all my intellectual property. Jews some would call them, in fact. That is how the cabal works. steal IP, hire cheepy to maintain, through US citizen out on the street. Those companies never last in reality after their funding because tech moves on, and they are left maintaining whereas someone else creates a better mousetrap that one ups them.