# isKnownParameter

> Whether a parameter's code is defined by its vocabulary version. cas codes and x- vocabularies are always accepted (CAS numbers outside the equivalence table are substances in mg/L).

> **isKnownParameter**(`parameter`): `boolean`

Whether a parameter's code is defined by its vocabulary version. `cas`
codes and `x-` vocabularies are always accepted (CAS numbers outside the
equivalence table are substances in mg/L).

## Parameters

### parameter

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

## Returns

`boolean`