The file is a compressed archive created using the 7-Zip archiver . The name suggests it may be the first part of a "split" archive or a container for files related to Digital Command Language (DCL) , a scripting language common in OpenVMS environments. Technical Breakdown of .7z Files
: It theoretically supports file sizes up to 16 billion GB (16 exbibytes), making it ideal for large dataset backups. DCL01.7z
If you see other files like DCL02.7z or DCL01.7z.001 in the same folder, this is a multi-part archive . You must have all parts present in the same directory to successfully extract the data. The file is a compressed archive created using