Determining the page mode (Add, View, Change, coPy, Delete, List) can be
very tricky, depending on how the user arrived at the current page mode.

$_REQUEST['PME_sys_operation'] may or may not be set

If the above is not set then one of the following may be set.

$_REQUEST['PME_sys_canceladd']    (if set) returns Cancel
$_REQUEST['PME_sys_cancelchange'] (if set) returns Cancel
$_REQUEST['PME_sys_cancelcopy']   (if set) returns Cancel
$_REQUEST['PME_sys_canceldelete'] (if set) returns Cancel
$_REQUEST['PME_sys_cancelview']   (if set) returns Cancel

$_REQUEST['PME_sys_moreadd']      (if set) returns More

$_REQUEST['PME_sys_morechange']   (if set) returns Apply

$_REQUEST['PME_sys_saveadd']      (if set) returns Save
$_REQUEST['PME_sys_savechange']   (if set) returns Save
$_REQUEST['PME_sys_savecopy']     (if set) returns Save
$_REQUEST['PME_sys_savedelete']   (if set) returns Save

-----

// set a variable which could be used with DATE fields
// in order to display (or suppress) a datepicker popup.
// $date_picker_mode_status is impacted by Apply and More buttons
// and to be displayed in Add, Change, coPy modes.

$date_picker_mode_status = 0;

if(array_key_exists('PME_sys_operation', $_REQUEST)){

	switch($_REQUEST['PME_sys_operation'])
	{
		Case 'Add':
		Case 'Change': // when change is accessed from View mode
		Case 'PME_op_Add':
		Case 'PME_op_Apply':
		Case 'PME_op_Change': // when change is accessed from List mode
		Case 'PME_op_Copy':
		Case 'PME_sys_moreadd':
			$date_picker_mode_status = 1;
			break;
		default:
			break;
	}

}elseif(isset($_REQUEST['PME_sys_morechange']) && $_REQUEST['PME_sys_morechange'] == 'Apply'){

	$date_picker_mode_status = 1;

}

-----


if(!isset($_REQUEST['PME_sys_operation']) && !isset($_REQUEST['PME_sys_moreadd']) && !isset($_REQUEST['PME_sys_morechange'])){

   echo "\n".'<table class="container"><tr><td>Company Filter</td><td>';

   for($i=65; $i<91; ++$i) {

      echo "\n".'<a href="'.basename($_SERVER["PHP_SELF"]).'?fl2='.chr($i).'">'.chr($i).'</a>';

      echo ($i < 90) ? ' - '."\n" : "\n";

   }

   echo "\n".'</td></tr>';

   echo "\n".'<tr><td>Last Name Filter</td><td>';

   for($i=65; $i<91; ++$i) {

      echo "\n".'<a href="'.basename($_SERVER["PHP_SELF"]).'?fl3='.chr($i).'">'.chr($i).'</a>';

      echo ($i < 90) ? ' - '."\n" : "\n";

   }

   echo "\n".'</td></tr><tr><td colspan="2"><a href="'.basename($_SERVER["PHP_SELF"]).'?fl2=&fl3=">List All</a></td></tr></table>';

}


-----  // An attempt to
// 1. apply $_SESSION['user_id'] to fields posted_by_id & last_update_by_id
// 2. manage the `deleted` field status
// 3. prevent Add mode, normally handled via custom user registration form

if(isset($_REQUEST['PME_sys_operation'])){

   // PME_sys_operation: Add, PME_op_Add, PME_op_Change, PME_op_Copy, PME_op_Delete, PME_op_View

	switch($_REQUEST['PME_sys_operation'])
	{
		Case 'Add':
		Case 'PME_op_Add':
			$opts['cgi']['overwrite']['deleted'] = '0';
			$opts['cgi']['overwrite']['posted_by_id'] = $_SESSION['user_id'];
			break;

		Case 'Change':
		Case 'PME_op_Change':
			$opts['cgi']['overwrite']['deleted'] = '0';
			$opts['cgi']['overwrite']['last_update_by_id'] = $_SESSION['user_id'];
			break;

		Case 'PME_op_Copy':
			$opts['cgi']['overwrite']['deleted'] = '0';
			$opts['cgi']['overwrite']['posted_by_id'] = $_SESSION['user_id'];
			break;

		Case 'PME_op_Delete':
			$opts['cgi']['overwrite']['deleted'] = '1';
			$opts['cgi']['overwrite']['last_update_by_id'] = $_SESSION['user_id'];
			break;

		default:
			// null
			break;
	}

}

// PME_sys_moreadd: More

if(isset($_REQUEST['PME_sys_moreadd']) && $_REQUEST['PME_sys_moreadd'] == 'More'){
	$opts['cgi']['overwrite']['deleted'] = '0';
	$opts['cgi']['overwrite']['posted_by_id'] = $_SESSION['user_id'];
}

// PME_sys_morechange: Apply

if(isset($_REQUEST['PME_sys_morechange']) && $_REQUEST['PME_sys_morechange'] == 'More'){
	$opts['cgi']['overwrite']['deleted'] = '0';
	$opts['cgi']['overwrite']['posted_by_id'] = $_SESSION['user_id'];
}

if(array_key_exists('PME_sys_moreadd', $_REQUEST) || (isset($_REQUEST['PME_sys_operation']) && $_REQUEST['PME_sys_operation'] == 'Add')){
	$opts['cgi']['overwrite']['deleted'] = '0';
}

if(isset($_REQUEST['PME_sys_operation']) && $_REQUEST['PME_sys_operation'] == 'Add'){

	die('Add function disabled (users must Register, or be created by copying the profile of an existing user and editing the user name, password, user level, etc.)');

}

if(isset($_REQUEST['PME_sys_moreadd']) && $_REQUEST['PME_sys_moreadd'] == 'More'){

	die('Add function disabled (users must Register, or be created by copying the profile of an existing user and editing the user name, password, user level, etc.)');

}

if(isset($_REQUEST['PME_op_Copy']) && $_SESSION['user_level'] < 500){

	die('Add function disabled (users must Register, or be created by copying the profile of an existing user and editing the user name, password, user level, etc.)');

}