The sid file contains installation and product authorization information. It is used by the deployment wizard.
The name of the file is something like sas94_xxxxxx_yyyyyyyy_zzz.txt (xxxxxx = order number, yyyyyyyy = site number (setnumid), zzz is the operating system that the licence is valid for.)
The sid file is located in the sid_files directory directly under the software depot's root directory.