# parameterKey

> Canonical identity of a parameter: the welldot code when the parameter is (or resolves to) a vocabulary entry, otherwise vocabulary:code. A welldot code and its CAS equivalent produce the same key.

> **parameterKey**(`parameter`): `string`

Canonical identity of a parameter: the `welldot` code when the parameter
is (or resolves to) a vocabulary entry, otherwise `vocabulary:code`.
A `welldot` code and its CAS equivalent produce the same key.

## Parameters

### parameter

[`Parameter`](/core/api/type-aliases/Parameter)

## Returns

`string`