rfc/ext_debugging is a SAP Parameter attribute which is used to control Activate HTTP-Debugging for RFC information. This is available within R/3 SAP systems depending on the version and release level.
Below is the standard documentation available and a few details of the attributes values .
Activate external (HTTP) debugging for RFC
Value range: <(><<)>0,1,2,3>
0
Deactivate profile parameters
1
Activate debugging for external partners
2
Activate debugging for SAP Web partners
3
Activate debugging for all
See SAP Parameter Documentation for full SAP documentation for this profile parameter.