_POST is:

Array
(
)

Page source code:

<?php 

header ('Content-Type: text/html; charset=iso-8859-1');

?>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
</head>
<body><?php

echo "<p> _POST is: </p> <pre>";
echo htmlspecialchars(print_r($_POST, true)); 
echo "</pre>"

?>
<form action="/latin-1-form.php" method="post">
<input type="textarea" name="this-is-a-textarea">
<input type="submit" name="Submit me!">
</form>
<?php 

echo "<p> Page source code: </p><pre>";
echo htmlspecialchars(file_get_contents("latin-1-form.php"));
echo "</pre>"

 ?>
</body></html>