Re: Why does simply creating a diversion produce output?

[Tadziu Hoffmann]

> .di d
> foo
> .di
> .rm d

Output is only sent to the diversion when a break occurs,
either explicitly with .br, or when enough text has been
collected to fill a line, or in no-fill mode.  Otherwise,
the diversion remains empty, but a partially collected
line exists when the end of input is encountered.
This causes a page to be begun, but since the partially
collected line is not forced out, the page remains empty.

Try the following variations

  .di d
  foo
  .br
  .di
  .rm d

and

  .di d
  foo
  .di
  .rm d
  .br

to see this.