PHP, input verification

In this PHP example, we allow input as ubc, vch, others. The input is not case sensitive and allow users some typo, such as add . between letters such as u.b.c., also type others as other.
//First remove all . and convert to lower case, using PHP function trim to ignore white spaces.
$site=strtolower(str_replace(".", "",trim($_POST['site'])));
//Create an array containing strings allowed
 $site_allow = array("ubc","vch","others","other");
//Using PHP function in_array to check string $site match any element of the array
  if(!in_array($site,$site_allow)){
     $record['error'][] = 'Invalid site category';
   }