How to understand GM_xmlhttpRequest parameter "binary"

Question

I tested below code:

`GM_xmlhttpRequest({ method: 'POST', url: "some url", data: "a1b2", binary: false});

GM_xmlhttpRequest({ method: 'POST', url: "some url", data: "a1b2", binary: true});`

I used Fiddler to check what's really send. but seems the two code sent same raw data by http. I also tested the code below

GM_xmlhttpRequest({ method: 'POST', url: "some url", data: new Blob([1,2,3]), binary: false});

GM_xmlhttpRequest({ method: 'POST', url: "some url", data: new Blob([1,2,3]), binary: true});

but the two code send identical raw data