1. A computing system for specifying one or more validation rules for validating data included in one or more fields of elements of a plurality of elements of a dataset, the computing system including: a processor; and a memory in communication with the processor, the memory storing an execution environment, the execution environment comprising: a processing module configured to evaluate a conditional expression and determine whether to apply one or more validation rules to at least one element of a dataset; and a user interface module that generates a user interface that renders a plurality of cells and that configures validation rules with validation parameters, the cells arranged in a two-dimensional grid that comprises: one or more first subsets of the cells extending in a first direction of the two-dimensional grid, each first subset associated with a respective field of an element of the plurality of elements of the dataset; second subsets of the cells extending in a second, different direction of the two-dimensional grid, with the second subsets associated with a respective validation rule; and a set of condition cells having an input element that receives a conditional expression that includes an operation and a value, the set of condition cells extending in the second direction of the two-dimensional grid, with cells in the set of condition cells being associated with one or more respective fields; with the processing module configured to: apply one or more validation rules to at least one field of an element of a dataset according to the value in a given one of the condition cells, with the given one of the condition cells having a given conditional expression to satisfy, with satisfaction of the given conditional expression causing application of a validation rule associated with the given one of the condition cells to the at least one field that includes the entered value.