---
title: isExternal
framework: foundation
role: symbol
role_heading: Instance Property
path: foundation/xmldtdnode/isexternal
---

# isExternal

True if the system id is set. Valid for entities and notations.

## Declaration

```swift
var isExternal: Bool { get }
```

## See Also

### Managing DTD Identifiers

- [notationName](foundation/xmldtdnode/notationname.md)
- [publicID](foundation/xmldtdnode/publicid.md)
- [systemID](foundation/xmldtdnode/systemid.md)