# Canonical identity: one operation, different names

[Concepts explained](README.md)

**Canonical** means the agreed common form used behind different spellings. An **ID**, or identifier, is a label that tells one thing apart from another.

Pliro has canonical identities for standard-library operations. The English name `length` and Dutch name `lengte` both refer to `core.length`. They count according to the same language rules.

## A label behind the label

Think of a museum object with an English card and a Dutch card. The display text differs, but both cards refer to the same object number.

An **alias** is an alternative name for the same thing. In this context it means a localized API spelling. That differs from a variable alias that shares a list, although both ideas involve more than one name.

```pliro
# language: en
say length([10, 20, 30])
```

This prints `3`. You use the source spelling `length`. The documentation label `core.length` is not a source namespace you should substitute into the program.

## Your names and messages

Changing syntax locale does not translate user-created variable names, strings, or comments. Those belong to your program's content. Pliro translates the language-defined spellings while keeping their shared meaning.

Try finding the canonical ID at the top of two corresponding built-in reference pages. Their source names may differ; the ID should match.

[Localization](../guides/localization.md) · [API](api.md)