Dunno about a book, but if a checkbox isn't checked, the browser doesn't send the value in the body of the submission.
Thus, PHP4 really isn't the problem, it's just how HTTP works.
Best is to do something like:
// submission form
<FORM METHOD=POST>
<INPUT TYPE=CHECKBOX name=dozen VALUE="12">Dozen
<INPUT TYPE=CHECKBOX name=bdozen VALUE="13">Baker's dozen.
</form>
// processing script.
<?
$fields=array('dozen', 'bdozen');
foreach($fields as $field)
{
// you do whatever you want here!
AUserFunction($_REQUEST[$field]);
}
?>
Pretty simple, no?
