How support claims are tested
Compatibility Methodology
What the Compatibility Lab measures, where documented limits come from and where a result is a judgement.
On this page: What is measuredWhere field limits come fromWhat is a judgementThe plain fallback
What is measured
- Grapheme count — user-perceived characters, via the browser's text segmenter.
- Code points — individual Unicode scalar values, which is how many platforms count.
- UTF-16 units and UTF-8 bytes — because some fields count one of these instead.
- Script and direction — detected from the character ranges present.
- Risk markers — combining marks, enclosing marks, variation selectors, emoji, zero-width and bidi control characters.
Where field limits come from
Each limit in the lab's table is taken from the platform's public help documentation or from the behaviour of its current rename screen at the time of writing, and is labelled with how that platform appears to count. Limits change; when you see a difference, tell us through the contact page with a link.
What is a judgement
Whether a specific symbol is filtered, whether moderation will act and how a name renders on a device we have not tested are judgements, and the lab says so rather than reporting them as pass or fail.
The plain fallback
The lab reverses the letter maps to recover a plain Latin spelling and strips outer decoration. This is the version to keep for any field that rejects the styled one.