rdisp/max_hold_time is a SAP Parameter attribute which is used to control Maximum hold time of work process 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 .
This parameter defines the maximum time that a work process can wait for
SAP GUI input in a way that blocks other requests.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.