rdisp/acl_file is a SAP Parameter attribute which is used to control Access Control List for SAP GUI connections 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 specifies the file that the (ABAP) dispatcher uses as an
access control list (ACL) for the access authorizations for connections
with SAP GUI. If the profile parameter is set, the file must exist and
its syntax be correct. If this is not the case, the (ABAP) dispatcher
ends.
The syntax of the ACL file is described in
See SAP Parameter Documentation for full SAP documentation for this profile parameter.