PAQJ
From Just Solve the File Format Problem
PAQJ is a compressed archive utility for DOS, and its .QAR file format. Almost all of the information about it is in Polish. It was apparently developed by Marcin Kowalczyk, and something called Qrczak.
It predates the PAQ family of formats, so is presumably not related to it.
Identification
QAR files begin with ASCII "Qrck
". They end with "Qrck
" followed by bytes 0x00 0x00
.