This is the scale they use, reproduced from their table. There wasn't a great way to reproduce the table here, so I used dokuwiki table formatting (since that's what I use). I hope it's readable enough (or can be easily converted to whatever table format you like better). (Edited: Fixed formatting errors)

  ^ Level ^ Color ^ Significance Category ^ Key Observable Criteria ^
  | 0 | White | Insignificant | Consistent with known natural phenomena. |
  | 1 | Green | Normal Natural Variation | Minor deviations, likely natural variations. |
  | 2 | Yellow | Meriting Attention | Non-gravitational acceleration exceeding cometary models. Single major anomaly in trajectory, composition, or morphology. Non-gravitational acceleration is marginally inconsistent with measured outgassing. |
  | 3 | Yellow | High Confidence Anomaly | Non-gravitational acceleration vastly exceeding maximum cometary outgassing given absence or weakness of visible coma. Multiple persistent anomalies across observable categories. No satisfactory natural explanation after a comprehensive analysis. |
  | 4 | Yellow | Anomaly Meeting Potential Technosignature Criteria | Non-gravitational acceleration exceeding cometary models. Spectral signatures absent in known asteroid taxonomy, including anomalous spectrum inconsistent with solar reflection. Albedo variations inconsistent with known materials. Deviation from Keplerian hyperbolic orbit inconsistent with outgassing models. Unusual shape inferred from lightcurve of reflected sunlight. Trajectory anomalously aligned with planetary orbital planes or selective inner planet targeting. |
  | 5 | Orange | Suspected Passive Technology | Unusual speed. Strong, persistent indicators of artificial, non-operational origin. Surface composition inconsistent with cosmic-ray bombardment for implied age or velocity. Absence of cometary activity despite substantial non-gravitational acceleration. |
  | 6 | Orange | Suspected Active Technology | Level 5 criteria plus at least one of the following: (i) Signs of being operational (e.g., maneuvers, signals); (ii) Electromagnetic signals in non-natural origin; (iii) Trajectory changes incompatible with gravitational or outgassing models; (iv) Detection of deployed sub-objects. (iv) Artificial illumination or heat that cannot be explained by solar irradiation. |
  | 7 | Orange | Suspected Active Technology with Unclear Intent | Level 6 criteria plus at least one of: (i) Responsive behavior to observations; (ii) Signals of unknown purpose; (iii) Operational intent that cannot be determined or appears potentially hostile. |
  | 8 | Red | Confirmed Technology (No Impact) | Direct investigation confirms extraterrestrial artificial origin. No collision trajectory. |
  | 9 | Red | Confirmed Technology (Regional Impact) | Confirmed extraterrestrial artificial origin. Impact trajectory with regional consequences. |
  | 10 | Red | Confirmed Technology (Global Impact) | Confirmed extraterrestrial artificial origin. Impact trajectory with global terrestrial consequences. |