rdisp/autojavauser is a SAP Parameter attribute which is used to control Specifies the user for automatic AUTOJAVA processing 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 .
With this parameter an ABAP user can be assigned to the AUTOJAVA program
See SAP Parameter Documentation for full SAP documentation for this profile parameter.