demo page

test iframe w/ complex args src:

<iframe src="https://www.econ.msu.ru/sys/rpc.php?cmd=echo&amp;a=1&amp;b=2&amp;c[d]=3&amp;url=https%3A%2F%2Fwww.econ.msu.ru%2Fsys%2Frpc.php%3Fcmd%3Decho%26id%3D1%26pid%3D0%26arg%5Bx%5D%3Dtt" width="100%" height="300" marginwidth="0"></iframe>