rdisp/myname is a SAP Parameter attribute which is used to control Name of the local Application Server 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 parameter is set by the system automatically and identifies an
instance uniquely. A table that assigns the instance names to existing
TCP connections is set up in the messager server at runtime.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.