YAML syntax

Following is an introduction to the YAML syntax. If you are familiar with YAML, skip to the TYPO3 specific information:

See also

A good general introduction to YAML syntax, basic data types, etc.:

The TYPO3 coding guidelines for YAML define some basic rules to be used in the TYPO3 core and extensions. Additionally, yaml has general syntax rules.

  • File ending .yaml
  • Indenting with 2 spaces (not tabs). Spaces MUST be used. You MUST use the correct indenting level.
  • Use UTF-8
  • All text is case-sensitive
  • Enclose strings with single quotes (‘’)


The following MUST be adhered to in order to produce valid syntax:

  1. Use spaces, not tabs to indent
  2. Identing is not optional. It is used to define the hierarchy of the data

To get a better understanding of YAML, you might want to compare YAML with PHP arrays:


$a = [
    'key1' => 'value',
    'key2' => [
        'key2_1' => 'value'

$b = [


# mapping (key / value pairs)
  key1: 'value'
    key2_1: 'value'

# sequence (list)
  - 'apples'
  - 'oranges'
  - 'bananas'