processed xml messages

In sxmb_moni, I have selected the processed xml messages and viewed one of success message. Under MsgID I have 3 sets of drop down menu

1.Inbound Message(CENTRAL)

2.Receiver Grouping

3. Response

Again each drop down meanu has 3 folder options

1.SOAP Header

2. SOAP Body

3. Payloads

Could you please tell me what are these Inbound Message(CENTRAL), Receiver Grouping and Response represent??

thanks

kumar