x
<html><body><h1>The input pattern attribute</h1><form action="/action_page.php"> <label for="country_code">Country code:</label> <input type="text" id="country_code" name="country_code" pattern="[A-Za-z]{3}" title="Three letter country code"><br><br> <input type="submit"></form><p><strong>Note:</strong> The pattern attribute of the input tag is not supported in Safari 10 (or earlier).</p></body></html>