Each setting can include validation options. Validation options enable you to apply additional constraints to the data that a setting can store, such as a minimum or maximum value, or a regular expression. The setting's `type` determines the available validation options. You can include a validation option for a setting using the validation `name` and a corresponding `value`. The appropriate value depends on the setting type to which the validation applies. The following table outlines the available validation options with supported types for applying constraints to a setting: | Validation option | Description | Supported types | Example | |---|---|---|---| | Minimum length | The minimum length of a text value. |

single_line_text_field
multi_line_text_field

[[extensions.settings.fields.validations]]
 name = "min"
 value = "8"

| | Maximum length | The maximum length of a text value. |

single_line_text_field
multi_line_text_field

[[extensions.settings.fields.validations]]
 name = "max"
 value = "25"

| | Regular expression | A regular expression. Shopify supports [RE2](https://github.com/google/re2/wiki/Syntax). |

single_line_text_field
multi_line_text_field

[[extensions.settings.fields.validations]]
 name = "regex"
 value = "(@)(.+)$"

[[extensions.settings.fields.validations]]
 name = "choices"
 value = "["red", "green", "blue"]"

[[extensions.settings.fields.validations]]
 name = "min"
 value = "2022-01-01"

[[extensions.settings.fields.validations]]
 name = "max"
 value = "2022-03-03"

| | Minimum datetime | The minimum date and time in [ISO 8601](https://www.iso.org/iso-8601-date-and-time-format.html) format. | `date_time` |

[[extensions.settings.fields.validations]]
 name = "min"
 value = "2022-03-03T16:30:00"

| | Maximum datetime | The maximum date and time in [ISO 8601](https://www.iso.org/iso-8601-date-and-time-format.html) format. | `date_time` |

[[extensions.settings.fields.validations]]
 name = "max"
 value = "2022-03-03T17:30:00"

[[extensions.settings.fields.validations]]
 name = "min"
 value = "9"

[[extensions.settings.fields.validations]]
 name = "max"
 value = "15"

[[extensions.settings.fields.validations]]
 name = "min"
 value = "0.5"

[[extensions.settings.fields.validations]]
 name = "max"
 value = "1.99"

[[extensions.settings.fields.validations]]
 name = "max_precision"
 value = "2"