# Output formats

This section deals with individual output-format topics.

The command line option `--output-format=`format chooses an output format. Supported format are `u-ctags`, `e-ctags`, `etags`, `xref`, and `json`.

`u-ctags`, `e-ctags`

  `u-ctags` is the default output format extending the Exuberant Ctags output format (`e-ctags`).

  `--format=1` and `--format=2` are same as `--output-format=e-ctags` and `--output-format=u-ctags` respectively.

  See man page tags (5) for details. The difference between `u-ctags` and `e-ctags` are marked as “EXCEPTION”. Additional changes in Universal Ctags are described in Changes to the tags file format.

`etags`

  Output format for Emacs etags.

  See the description of `-e` option in ctags(1).

`xref`

  A tabular, human-readable cross reference (xref) format. `--output-format=xref` can be abbreviated as `-x`.

  See section Xref output for details.

`json`

  JSON format.

  See ctags-client-tools(7).

- Changes to the tags file format
  - `F` kind usage
  - Reference tags
  - Pseudo-tags
  - Truncating the pattern for long input lines
  - Parser specific fields
  - Parser specific extras
  - Parser specific parameter
- Xref output
  - Customizing xref output