Would you like to [replace more defines for constant values](https://github.com/ChrisDodd/btyacc/blob/bdaaa2ab318d94ea1e602742a4e099296eb59551/defs.h#L68) by [enumerations](https://en.wikipedia.org/wiki/Enumerated_type#C_and_syntactically_similar_languages) to stress their relationships?