When you edit a specific form field, you can add "extended validation". This lets you require that information be entered in a specific format before the registration data can be submitted.

In the example below, there is an input field where players should enter a receipt number. By adding a "minimum character" validation, you can require that the player enters a number that is at least 10 digits long.

When you add validation, you can add a validation message, which can help your players understand why their input was rejected and what the correct format should be. Read more here.

Types of validation

Only numbers	will only accept numerals 0 – 9
Only letters	will only accept letters (from almost all alphabets), space, and dash (-)
Max characters	limits the number of characters
Min characters	requires a minimum number of characters
Own regular expression	lets you write a regex to control the input (this is an advanced setting)
Valid phone	requires an 8-digit number (for other phone number formats, see example below)
Valid email	requires a valid email address format (allows letters, numbers, and specific characters, checks that there is an @ symbol and a .)
Remove special characters	will reject anything with the following characters: ЈҐў$Ђ¤©®§™°є+#µ<>%([)]??ї!?-'",.\|`^«»«»~&:{;}
JavaScript event	lets you add a custom function (this is an advanced setting)
File	choose from .txt, .xlsx, .xls, .docx, .doc, .pdf, .psd, .svg, .eps, .png, .jpg, .jpeg, .gif, .ico, .mp4, .mov
Min. age	requires an age that is greater than or equal to the entered number
Min. date	disables dates in the calendar before the given date
Max. date	disables dates in the calendar after the given date

You can use more than one type of validation. For example, you can require a number that is exactly 12 digits long by selecting:

only numbers
max characters = 12
min characters = 12

But note that you can only write one validation message, so the message should explain the correct format clearly.