The Challenge 1 Input Files and Format description is in Appendix A of the Challenge 1 Problem Formulation.
The Grid Optimization Competition Challenge 1 uses a set of 4 ASCII encoded text files for the input data of each problem instance:
Power Flow Network Configuration Data File (case.raw)
Cost Function Data File (case.rop)
Participation Factor Data File (case.inl)
Contingency Description Data File (case.con)
These 4 files are formatted according to some common data file formats used in the power system industry. Only some of the fields in the files are used for Challenge 1. The Input Files and Format document will provide a detailed description of these formats and which of those elements are used by Challenge 1 or otherwise need to be understood by Entrants.