rdisp/vb_included_server is a SAP Parameter attribute which is used to control List of the update server used for dispatching 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 .
The update dispatching can be influenced using the parameter
rdisp/vb_included_server. The parameter defines all update servers that
are to be considered during dispatching.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.