---
type: "fhirpath-operator"
title: "FHIRPath Operator: is (is)"
operator: "is"
category: "Types"
section: "6.3.1"
source: "fhirpath/operations.json"
---
# FHIRPath Operator: is (is)
If the left operand is a collection with a single item and the second operand is a type identifier, this operator returns `true` if the type of the left operand is the type specified in the second operand, or a subclass thereof. If the input value is not of the type, this operator returns `false`. If the identifier cannot be resolved to a valid type identifier, the evaluator will throw an error. If the input collections contains more than one item, the evaluator will throw an error. In all other cases this operator returns `false`.

A _type specifier_ is an identifier that must resolve to the name of a type in a model. Type specifiers can have qualifiers, e.g. `FHIR.Patient`, where the qualifier is the name of the model.

``` fhirpath
Bundle.entry.resource.all($this is Observation implies status = 'finished')
```

This example returns `true` if all Observation resources in the bundle have a status of finished.
## Summary
- **Category**: Types
- **Section**: `6.3.1`
- **Left Argument**: `Any`
- **Right Argument**: `type specifier`
- **Return Type**: `Boolean`
- **Empty Input Result**: `false`
- **Errors on Multiple Input**: `true`
## Description
Returns `true` if the type of the left operand is the type specified in the second operand, or a subclass thereof. The left operand must be a collection with a single item and the second operand must be a type identifier. Returns `false` if the input value is not of the specified type.
## Type Mapping
- `Any-TypeIdentifier`