A sequence of characters usually defining a string of
text.  The first byte identifies the length, in bytes,
of the rest of the string.

Lstrings are often used in the Pascal programming
language but are seen in only a few DOS system
services (ASCIIZ strings are the standard).

In assembly language:

sMyFile db 12,'c:myfile.txt'
  PSPs contain an Lstring of the command-line text.
  DOS fn 4b00H uses an Lstring in its parameter block.