This tab displays the parameter names and values contained a POST request. The mime type displayed on this tab is the encoding scheme used to upload data and if usually one of the following for HTML based forms:
This is the same format as a query string, but the string is passed in the request body rather than the URL.
This passes the raw, unescaped data in the the POST body by using a marker to define the data boundaries.
The size column shows the total size in bytes of the parameter name and value in the HTTP request message.