The KEYBOARDHINT attribute gives an indication on the kind of data the form field contains, to let the front-end adapt the keyboard accordingly.
KEYBOARDHINT = { DEFAULT | EMAIL | NUMBER | PHONE }
The KEYBOARDHINT attribute can be used to give a hint to the front-end, regarding the kind of data the form field will contain. According to this hint, the front-end will open the virtual keyboard adapted to the data type, especially useful when designing application forms for mobile platforms.
For example, when defining a numeric field with the attribute KEYBOARDHINT=NUMBER, the iOS device will display a numeric keyboard when entering data into that field.
Figure 1. Mobile application using a numeric keyboard
EDIT f23 = customer.cust_phone, KEYBOARDHINT=PHONE;