| # EnvelopeHeader constructor | |
| EnvelopeHeader(int numBytes, int numHandles, [EnvelopePresence](../../package-fidl_fidl/EnvelopePresence.md) presence, [EnvelopeContentLocation](../../package-fidl_fidl/EnvelopeContentLocation.md) contentLocation) | |
| ## Implementation | |
| ```dart | |
| EnvelopeHeader( | |
| this.numBytes, this.numHandles, this.presence, this.contentLocation); | |
| ``` | |