What 𝒰 means
Read it as a symbol defined by its author.
A script U can name one object in one paper and something else in another. Its style distinguishes it from plain U when a notation needs both; follow the writer's definitions rather than guessing from the letterform.
Why is 𝒰 a separate character?
It preserves a difference between mathematical symbols.
The 1999 Unicode proposal documented script and other styled letters already used in research mathematics and the sciences. The encoding grew out of STIX (Scientific and Technical Information Exchange), a publishing project to create a shared technical font set and make research documents easier to exchange. The proposal argued that letter style can change mathematical meaning, so the distinction needs its own searchable character.
What does 𝒰 mean when someone sends it?
The surrounding message decides whether it is notation or ornament.
Inside a formula, follow the author's local definitions. A script style alone cannot tell you what the letter names.
Part of the collection
What it means when someone sends it to you
2 readingsA symbol whose role is set by that author's notation.
Don't confuse it with
1
Questions people ask
1Why does 𝒰 look different in different fonts?
Fonts choose different defaults. In Unicode 18.0, the code charts show roundhand, while Cambria Math and STIX Two Math default to chancery; the styles are usually interchangeable in math.
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How to type or find 𝒰
- Also called
- script U · calligraphic U
- Search it as
- mathscr · mathcal · curly u · fancy u
- Shows up in
- Anything that takes text · its shape is whatever your font draws
𝒰\1D4B0\mathscr{U} for script or \mathcal{U} for calligraphic lettering; the selected math font controls the exact shape.𝒰 in an HTML document to encode this exact character.U, which can erase a distinction in mathematical text.Codes and encoding1 code points
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.