From Just Solve the File Format Problem
Dutch company producing ERP, CRM, HRM, financial, accounting and business software.
Exact for DOS v4.x - v7.x
- please note that the mentioned version numbers for these types of files are assumed based on preliminary research  since EFS is a proprietary file format. Details follow. (Maurice.de.rooij (talk) 03:59, 16 November 2012 (UTC))
A yearbook consists of 3 files:
- dat: file containing binary data (EFS format ("Exact File System"))), possibly encrypted with at least a username and/or password
- id: file containing mixed binary and human readable data to identify the yearbook
- lst: file containing mixed binary and human readable data with fieldnames from the yearbook