Aruba Networks PowerConnect W Clearpass 100 Software Deployment Manual page 250

The Conversion step should be used when the type of data displayed in the user interface is different from
the type required when storing the field.
For example, consider a form field displayed as a date/time picker, such as the expire_time field used to
specify an account expiration time on the create_user form. The user interface is displayed as a text field,
but the value that is required for the form processing is a UNIX time (integer value).
In this case, the Conversion function is set to NwaConvertOptionalDateTime to convert the string time
representation from the form field (for example, "2008-01-01") to UNIX time (for example, 1199145600).
The Validator for the expire_time field is IsValidFutureTimestamp, which checks an integer argument
against the current time.
The Value Formatter is applied after validation. This may be used in situations where the validator requires
the specific type of data supplied on the form, but the stored value should be of a different type. In the
expire_time field example, this is not required, and so the value formatter is not used. However, if the
Conversion function had not been used, and the Validator had been set to IsValidFutureDateTime (which
checks a string date/time value), then the Value Formatter would need to be set to
NwaConvertOptionalDateTime to perform the data conversion before the form processing.
250 | Guest Management ClearPass Guest 3.9 | Deployment Guide