## FhirFilterExpression type [​](/content/docs/sdk/core.fhirfilterexpression#fhirfilterexpression-type "Direct link to FhirFilterExpression type"/index.html)

The FhirFilterExpression type is the base type of all filter expressions.

**Signature:**

```typescript
export type FhirFilterExpression = FhirFilterComparison | FhirFilterNegation | FhirFilterConnective;
```

**References:** [FhirFilterComparison](/content/docs/sdk/core.fhirfiltercomparison), [FhirFilterNegation](/content/docs/sdk/core.fhirfilternegation), [FhirFilterConnective](/content/docs/sdk/core.fhirfilterconnective)