Wow I hate* that. I use bracket comments. They're cool cause they are bracket comments, so I use it in scripts to document pipelines. They are annoying cause they are bracket comments, in an interactive shell I have to type more and in TWO places. It's fun to reason-out how it works ;)

  $ echo foo | tr fo FO | sed 's/FOO/BAR/'
  BAR
  $ echo foo | ${IFS# tr fo FO | } sed 's/FOO/BAR/'
  foo

It's nice to have a way to both /* ... */ and // ... in shell scripts though:

  foo \
  | bar ${IFS Do the bar. Do it. } \
  | baz

* in the best possible way, like it's awful - I hate I didn't think of that