The variable numbering techniques include binary, categorical, and ordinal variables. Which is different sometimes. Here is an example of variable numbering example.
Reference
1. Investigating the impact of influential factors on crash types for autonomous vehicles at intersections
2. Kim, Eui-Jin, Min-Ji Kang, and Shin Hyoung Park. "Deep survival analysis model for incident clearance time prediction." Journal of Intelligent Transportation Systems (2024): 1-14.