---
name: "TIFFSetTagExtender"
section: "3tiff"
platform: "linux"
package: "libtiff-dev"
version: "4.7.0-3+deb13u3"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/TIFFSetTagExtender"
---

# TIFFSetTagExtender(3tiff)

register the merge function for user defined tags as an extender callback with libtiff

## NAME

TIFFSetTagExtender - register the merge function for user defined tags as an extender callback with libtiff

## SYNOPSIS

```
#include <tiffio.h>
```

- **TIFFExtendProc TIFFSetTagExtender(TIFFExtendProc extender)**

  ## DESCRIPTION

*TIFFSetTagExtender()* is used to register the merge function for user defined tags as an extender callback with **libtiff**. A brief description can be found at *Defining Application Tags*.

**NOTE:**

*TIFFSetTagExtender()* cannot be used to extend custom directories (for example EXIF, GPS or other custom directories). Only the TIFF directory can be extended with additional tags.

## SEE ALSO

*libtiff* (3tiff), *Defining New TIFF Tags* (3tiff), *TIFFMergeFieldInfo* (3tiff)

## AUTHOR

LibTIFF contributors

## COPYRIGHT

1988-2022, LibTIFF contributors