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<html><body><h1>The input placeholder attribute</h1><form action="/action_page.php"> <label for="phone">Enter a phone number:</label><br><br> <input type="tel" id="phone" name="phone" placeholder="123-45-678" pattern="[0-9]{3}-[0-9]{2}-[0-9]{3}"><br><br> <small>Format: 123-45-678</small><br><br> <input type="submit"></form></body></html>