Complete documentation for "DCHECK" can be found on pages 131 to 135 of the
document that can be found at the following URL:
ftp.maltedmedia.com/coco/MANUALS/TANDY/SOFTWARE/TANDY_OS9
File name:
OS-9 Level I (1983)(Tandy)(pdf).7z

What I used to check '/D0':
/D1/DCHECK -BPW=/D1 /D0