Isbn Zend_Validate_Isbn allows you to validate an ISBN-10 or ISBN-13 value. Supported options for Zend_Validate_Isbn The following options are supported for Zend_Validate_Isbn: separator: Defines the allowed separator for the ISBN number. It defaults to an empty string. type: Defines the allowed type of ISBN numbers. It defaults to Zend_Validate_Isbn::AUTO. For details take a look at this section. Basic usage A basic example of usage is below: isValid($isbn)) { // isbn is valid } else { // isbn is not valid } ]]> This will validate any ISBN-10 and ISBN-13 without separator. Setting an explicit ISBN validation type An example of an ISBN type restriction is below: setType(Zend_Validate_Isbn::ISBN13); // OR $validator = new Zend_Validate_Isbn(array( 'type' => Zend_Validate_Isbn::ISBN13, )); if ($validator->isValid($isbn)) { // this is a valid ISBN-13 value } else { // this is an invalid ISBN-13 value } ]]> The above will validate only ISBN-13 values. Valid types include: Zend_Validate_Isbn::AUTO (default) Zend_Validate_Isbn::ISBN10 Zend_Validate_Isbn::ISBN13 Specifying a separator restriction An example of separator restriction is below: setSeparator('-'); // OR $validator = new Zend_Validate_Isbn(array( 'separator' => '-', )); if ($validator->isValid($isbn)) { // this is a valid ISBN with separator } else { // this is an invalid ISBN with separator } ]]> Values without separator This will return FALSE if $isbn doesn't contain a separator or if it's an invalid ISBN value. Valid separators include: "" (empty) (default) "-" (hyphen) " " (space)