Based on the search results and common practices in WooCommerce, here are the common data types used for custom fields:
1. Text: For short text inputs like names, titles, etc.
2. Textarea: For longer text inputs like descriptions or additional details.
3. Number: For numeric values like quantities, measurements, etc.
4. Date: For date inputs, often using a date picker.
5. Checkbox: For yes/no or true/false options.
6. Select (Dropdown): For choosing from predefined options.
7. Multi-select: For choosing multiple options from a list.
8. Radio buttons: For selecting one option from a small set of choices.
9. Email: For email address inputs.
10. URL: For website or link inputs.
11. File upload: For allowing customers to upload files.
12. Color picker: For selecting colors.
13. Password: For password inputs (with masked characters).
14. Hidden: For fields not visible to users but stored with the order.
15. Time: For time inputs.
16. Phone: For phone number inputs.
When creating custom fields in WooCommerce, it's important to choose the appropriate data type to ensure proper validation and formatting of the input data. Additionally, when mapping these fields to other systems like Dotdigital, you need to ensure that the data types are compatible between the two systems to avoid any data inconsistencies or sync issues.
Citations:[1] https://elementor.com/blog/woocommerce-custom-fields/
[2] https://support.dotdigital.com/en/articles/8199778-understanding-the-sync-process-from-woocommerce-to-dotdigital
[3] https://woocommerce.com/products/custom-fields-for-woocommerce/
[4] https://wpswings.com/blog/woocommerce-custom-fields/
[5] https://support.dotdigital.com/en/articles/8199779-map-woocommerce-customer-custom-fields-to-dotdigital-custom-data-fields