Fact · Dictation in your apps
MDN's data guidelines use the value preview when a browser's future stable version number is unknown or uncertain.
Checked against its source on October 17, 2026
In the source's own words
“when the future stable version number is unknown or uncertain”
browser-compat-data data guidelines (README), MDN Web Docs (Mozilla), GitHub, 2026, Choosing preview values.
Open the original- What it measures
- The guidelines explain the value preview in the compatibility data.
- What it does not show
- Preview is not a release. It says the feature is in a development build and may or may not reach a numbered release.