SSDP request packet understanding

  networking, protocols, python, scapy, upnp

I don’t know if it’s the right place to ask this question but I have a project where I have to create several ssdp request packets and I am having trouble understanding the ssdp request packet format. So I know there’s host, ST, Port and MX field in a ssdp request packet. My question is: is ST(search target) field the only field in the ssdp request packet which can constantly change and affect the response size? Or are there other fields which can change the response size I get?

A little more explanation on the project: So essentially I have to determine what field values of a ssdp request packet creates the highest response.

Source: Python Questions