1. A method comprising: receiving, at a computing device, first data entered into a first data-entry field mapped to a first node of a hierarchical data file written in XML, the first data intended for storage in the first node of the hierarchical data file; and validating, locally on the computing device and using one or more validation rules based at least in part on a schema containing logic governing the hierarchical data file, wherein at least one validation rule is configured to be a script-based rule, the first data received in real time and prior to permitting entry of second data into a second data-entry field mapped to a second node of the hierarchical data file, the second data intended for storage in the second node of the hierarchical data file, the one or more validation rules governing a node group of the hierarchical data file of which the first node is a part of, and validating being based on third data stored in at least a third node of the node group, the third data having been entered into a third data-entry field mapped to at least the third node.