# ParameterDefinition

> One entry of the welldot parameter vocabulary.

> **ParameterDefinition** = `object`

One entry of the `welldot` parameter vocabulary.

## Properties

### cas?

> `optional` **cas?**: `string`

Published CAS equivalence: a `cas` result with this code is this parameter.

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### charge?

> `optional` **charge?**: `number`

Ionic charge of that species (signed).

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### code

> **code**: `string`

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### form

> **form**: [`ParameterForm`](/core/api/type-aliases/ParameterForm)

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### group

> **group**: [`ParameterGroup`](/core/api/type-aliases/ParameterGroup)

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### label

> **label**: `string`

Canonical English label.

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### labels

> **labels**: `Record`\<`string`, `string`\>

Translations of `label`, keyed by BCP 47 language tag.

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### molar\_mass?

> `optional` **molar\_mass?**: `number`

Molar mass (g/mol) of the species the code is expressed as (e.g. N for
`nitrate_as_n`, CaCO₃ for alkalinities). Present for ions used in
ion-balance and hydrochemical derivations.

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### unit

> **unit**: [`ParameterUnit`](/core/api/type-aliases/ParameterUnit)