Email adress validation checks the accuracy of email addresses for you. Users will receive an error message if their input does not match the requirements set for a valid email address.

1. Error message
   If you need a different error message than the default error message wording, you can enter this error text for the Error message.

If you activate the validation Date, a calendar is displayed when users click in the input field.

You can limit the entry of the date to a certain period of time. This is useful when a meeting can only be scheduled between two specific dates, for example.

If users enter text in the input field, it will not be accepted.

1. Error message
   If you need a different error message than the default error message wording, you can enter this error text for the Error message.

1. Date format
   Frequently used date formats are available here.
   The following elements are available here:

Element	Meaning
yyyy	Year, four digits
yy	Year, two digits
MM	Month, two digits
dd	Day, two digits
HH	Hour, two digits, 00 to 23
hh	Hour, two digits, 00 to 12
mm	Minute, two digits

1. No time restrictions
   If you select No time restrictions, then your users will be able to enter any date.
2. Date range
   If users should enter a date that is within a specified period of time, then you can define this period using a Date range.
   Start date: Select the start date for your specified period of time.
   End date: Select the end date for your specified period of time.

1. Valid timespan
   You use Valid timespan to limit the date entered by the user to a maximum number of days before or after the form completion date.
   Days before completion date: The date entered must be within the period defined by the number of days before the completion date.
   Days after completion date: The date entered must be within the period defined by the number of days after the completion date.

When you need your users to enter dimensions or quantities, you can use Number validation to ensure that the value entered by your users is in fact a number. You can also specify a number range: the user’s value must then be within this range. Users will receive an error message if they enter a number that is larger or smaller.

1. Error message
   If you need a different error message than the default error message wording, you can enter this error text for the Error message.

1. Min. value
   You use Min. value to specify the smallest possible value that users can enter into the form field. Users will receive an error message if they enter a number that is smaller.

1. Max. value
   You use Max. value to specify the largest possible value that users can enter into the form field. Users will receive an error message if they enter a number that is larger.

1. Integers only
   Select Integers only if you want to prevent users from entering decimal numbers.

You use a regular expression to confirm that a character string (i.e. the input from your users) complies with a specific format.

For example, your users may need to enter their customer number into an input field. Let’s assume that the customer number always consists of two uppercase letters, two lowercase letters and six digits, for example ABcd123456.

You can use a regular expression to define this format for the customer number. When users enter their customer number, this number is compared with the pattern specified by the regular expression. Users will receive an error message if the character string that they input does not consist of two uppercase letters, two lowercase letters and six digits.

1. Error message
   If you need a different error message than the default error message wording, you can enter this error text for the Error message.

1. RegEx
   If you want to specify a character string with a regular expression, enter this expression into the RegEx field. A list of regular expressions for use cases that are frequently needed – and which you can customise as required – is already provided here.
   The following regular expressions are available to you out of the box.

Regular expression	Explanation
Numbers: ^[0-9]*$	This regular expression allows only digits (0–9) to be entered.
3-7 numbers: ^[0-9]{3,7}$	This regular expression allows only three to seven digits (0–9) to be entered.
5 numbers: ^[0-9]{5}$	This regular expression allows only five digits (0–9) to be entered.
Phone: ^[+]{0,1}[0-9\s-/]*	This regular expression allows only a phone number to be entered.
Letters: ^[a-zA-ZÁ-ÿöäüÖÄÜß\s-]*$	This regular expression allows only letters to be entered.
3 lowercase letters: ^[a-z]{3}$	This regular expression allows only three lowercase letters to be entered.
Amount: ^[0-9]{1,7}(.\d{2})?$	This regular expression allows only a number containing 1 to 7 digits, with an optional two-digit decimal value following a decimal point.

For more information about regular expressions, please see: https://en.wikipedia.org/wiki/Regular_expression

Postcode validation checks user input against postcodes (or zip codes) for selected countries.

1. Error message
   If you need a different error message than the default error message wording, you can enter this error text for the Error message.

1. Country
   Use Country to select the country for which your users are supposed to be entering a postcode.

1. Country selection
   If you have added a drop-down list with a country selection to your form, then you can select the list here. The postcode must then come from the country that users select from that list. As one example, only German postcodes will be accepted if users select Germany from the country list.

With the Number of characters validation, you specify the minimum and maximum number of characters that users are allowed to enter into an input field.

1. Error message
   If you need a different error message than the default error message wording, you can enter this error text for the Error message.

1. Min. no. of characters
   Use Min. no. of characters to enter the minimum number of characters that users must enter into the input field. Users will receive an error message if they do not enter enough characters.

1. Max. no. of characters
   Use Max. no. of characters to enter the maximum number of characters that users can enter into the input field. Users will receive an error message if they enter too many characters.

IBAN validation checks user input to confirm that it corresponds to the structure of an IBAN.

An IBAN always starts with a country code (e.g. ‘DE’ for Germany) and a 2-digit check number. This is followed by an 8-digit bank code and the account number (max. 10 digits). Account numbers that have fewer than 10 digits are padded with leading zeros.

1. Error message
   If you need a different error message than the default error message wording, you can enter this error text for the Error message.

1. Country
   Each country has its own IBAN format. If the IBAN needs to come from a specific country, use Country to select it. If you do not select a country, user input is checked only to confirm that it conforms to the basic IBAN structure.

1. Country selection
   If you have added a drop-down list with a country selection to your form, then you can select the list here. The IBAN must then come from the country that users select from that list. As one example, only a German IBAN will be accepted if users select Germany from the country list.

European Union VAT registration number validation checks user input to confirm that it corresponds to the structure of an EU VAT registration number. A European Union VAT registration number always starts with the 2-digit country code of the respective country, followed by nine to twelve digits, depending on the country. In some countries, the country code can be followed by letters as well as digits.

1. Error message
   If you need a different error message than the default error message wording, you can enter this error text for the Error message.

1. Country
   If the European Union VAT registration number needs to come from a specific country, use the country field to select it.

1. Country selection
   If the European Union VAT registration number should be checked against a country selected by users from somewhere else in the form, then you can link the validator to the corresponding form field. To do so, use Country selection to select the form field that provides the country selection from which users need to select a country. As one example, only a German EU VAT registration number will be accepted if users select Germany from the country list.

BIC validation checks user input to confirm that it corresponds to the structure of a BIC (Bank Identifier Code) – also known as a SWIFT code. A BIC always has the same structure: it consists of eight to eleven letters and digits that provide the sort code, country code, regional code and branch ID (optional).

1. Error message
   If you need a different error message than the default error message wording, you can enter this error text for the Error message.

Equal value validation can be used to compare user input between two input fields and confirm that these values are identical. If the values are not the same, then users are notified of this fact and can then correct their input. This offers a reliable way to catch typos.

Another common usage is when asking users to enter their email address twice – which is often done when users register an account online. This ensures that the email address submitted by the user is valid and correct.

1. Error message
   If you need a different error message than the default error message wording, you can enter this error text for the Error message.

1. Compare with
   Use Compare with to select the second input field whose contents must match the input from this input field.

Use Phone number validation to avoid incorrect user input when users are asked to enter telephone numbers. In addition, you can also specify that phone numbers must come from specific countries and/or require numbers to match certain types, such as fixed-line or mobile numbers.

Users will receive an error message if the phone number they enter has errors or does not meet your requirements.

1. Error message
   If you need a different error message than the default error message wording, you can enter this error text for the Error message.

1. Valid phone number types
   You can restrict the phone numbers that can be entered into this form field by number type. To do this, select a Phone number type.

1. Country
   Use Country to select the country for which your users are supposed to be entering a phone number. The validator then checks to confirm that the dialling code for the phone number entered matches the country code for the country specified.

1. Country selection
   If you have added a drop-down list or single choice form element with the data source 'country names' to your form, then you can select it here. The phone number must then come from the country that users select from that list. As one example, only phone numbers with a Spanish country code will be accepted if users select Spain from the country list.