sed regexp address range minus (or plus) number of lines

I have multiple ICS files that contain something like:

...
PRIORITY:4
DESCRIPTION:this
  was
  a
  triumph
COMPLETED:20180101T160000
...

I am in interested in addressing the DESCRIPTION key. The key DESCRIPTION can occur anywhere in the ICS file. It is _not_ always followed by the key COMPLETED. Using ed, I would do it like this:

/DESCRIPTION/;/^[^ ]/-1p

which results in:

DESCRIPTION:this
  was
  a
  triumph

However, sed does not seem to have that capability:

sed -n '/DESCRIPTION/,/^[^ ]/-1p' filename

results in > sed: -e expression #1, char 22: unknown command: `-' Is there a way to do what I want using sed? ## Solving this particular problem This problem can be solved by:

sed -n '/DESCRIPTION:/,/^\S/ { /\(DESCRIPTION\|^\s\)/p }' example.ics

But this feels very unwieldy and verbose. awk also does not seem to support /begpat/,/endpat/-1, so you would end up with something like:

BEGIN { endpat = "^(DESCRIPTION|\\s)" }
/^DESCRIPTION/, $0 !~ endpat {
    if ($0 ~ endpat) {print}
}