When using the FileMaker API for PHP to call a FileMaker script, you'll sometimes get this notice:
Notice: Only variable references should be returned by reference in C:\inetpub\www.somewebsite.com\data\FileMaker\Command.php on line 127
I'm still not sure what causes this notice to be displayed, but I do know how to prevent it from being displayed. Simply add the error silencing "@" symbol to the execute comand. For example...
// Create a "perform script" command.
$fm_request = $fm -> newPerformScriptCommand ( 'PHP - Layout', 'Some Script', $script_param );
// Execute the request.
$fm_result = @ $fm_request -> execute ();
And that should do it!