Explore the use of schema for input or output specification

This issue focuses on exploring and possibly implementing the use of schema as a way to describe input or output data. Specifically, this would be a way to describe column names, data types, and groupings of files using an existing standard of some kind.

The issue names no files, tests, or entry points. Start by reviewing how current input and output data are specified, then compare existing schema standards for column names, data types, and file groupings; the work is done when a standard and implementation scope are clearly established.

Written by the indexing model from the issue text.