| Code | Name | Focus | Used In |
|---|---|---|---|
| E1 | Request Input Entities | User input, payload | Signatures, Restrictions |
| E2 | Source & Frequency | IP, Geo, Sessions, RPS | Anomalies, Rate Limiting |
| E3 | Protocol & RFC Behavior | Method, UA, RFC, Structure | Restrictions, Flow Control |
| E4 | Client Behavior & Type | Browser features, click behavior | CI, Bot Detection, Interrogation |
