enque/server/acl_file is a SAP Parameter attribute which is used to control ACL (access control list) file of the Enqueue Server port 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 name of an access control list (ACL) file.
You can use an ACL to configure who is permitted to create a connection
to the enqueue server. The IP addresses of the clients form the basis of
the file.
The syntax of the ACL file is described under
See SAP Parameter Documentation for full SAP documentation for this profile parameter.