Second, ACL can read most sequential files and relational database tables directly, but esoteric and/or complex file structures may require “flattening” before they can be analyzed. This process may involve additional procedures and special programs to produce a copy of the original file in a format that ACL can accept. If the organization’s systems personnel perform the flattening process, the auditor must verify that the correct version of the original file was used and that all relevant records from the original were transferred to the copy for analysis.