The Free On-line Dictionary of Computing (30 December 2018):

Digital Linear Tape
DLT

    (DLT) A kind of magnetic tape drive
   originally developed by DEC and now marketed by Quantum.

   DLT drives implement the Digital Lempel Ziv 1 (DLZ1)
   compression algorithm in a combination of hardware and
   firmware.  They use a popular chip by Stac (now hi/fn)
   to do the string searching.  Counting, sorting and Huffman
   coding are done in firmware (with hardware support for the
   Huffman algorithm?).

   In April 1997 DLT drives can transfer 5 megabytes per second
   and can store 35 gigabytes on a single cartridge.
   Compression might roughly double these figures.

   (1997-04-05)