| Clue | Source | Date |
|---|---|---|
| Plus sign? | New York Times | 31 Aug 2019 |
| Plus sign? | ||
| Formal authorization | Newsday | 27 Feb 2018 |
| Official OK | USA Today | 25 May 2017 |
| Official OK | ||
| O.K. | ||
| Formal OK | ||
| Formal okay | ||
| Endorsement | ||
| Endorsement | ||
| Green light | ||
| Green light | ||
| Okay | ||
| Official okay | ||
| Formal okay | ||
| Formal okay | ||
| Endorsement |