DL_ is the extension given to files that are associated with Microsoft Windows operating systems. DL_ are files that are backup files for system link libraries dynamically saved in DLL files. This solution is often used in software distribution, because DL_ copies are compressed, which saves space on the data carrier. Also, if the DLL is damaged, you can restore it with a DL_ copy.

Compression of DL_ files is based on the CAB format. Such files can be generated and unpacked using the makecab command in the system console.