What is Program ID in Type "T" RFC's

Hello Gurus

Can anyone of you please try to clear my doubt what exactly is Program ID's in http type RFC in TA SM59

When I am checking any type T RFC in my PRD system i am able to see multiple type T RFCs but i am not able to understand what exactly is program ID in that connection.

In addition to that what exactly is purpose of differencet type of "Activation Type". What is meaning of each option.

Any help is appreciated

Regards,

SG