Dialog pipes (|) surrounding date format field

[bill]

40tude Dialog defaults to putting pipes (|) around "idt" for the
"Attribution Line" "Date format:" field which, from experimentation, the
pipes surrounding the "|idt|" seems to mean to format the date based on the
"Date:" header of the post I'm responding to.

Without the pipes, the "idt" seems to utilize the "Injection Date:" header
to formulate the on-date attribution line.

But... When I test this out with syntactically complicated formats, such as:
m"/"d"/"yyyy t
|m"/"d"/"yyyy t|
It's much harder to get the pipes to stick.

Sometimes they work. Sometimes they don't. Sometimes they disappear!
It's black magic when they work (which they eventually do, somehow).
Obviously I'm not completely understanding what these pipes accomplish.

Where is it documented how to use the pipes in the Dialog date format field?
It's not documented where you'd expect to see it documented (AFAICT).

Dialog: Help -> Help contents... ->
Contents -> Reference -> Date-Time Format Strings

Regards,
bill
--
Why did the redneck get colored pencils before he got his flu shot?
He heard that vaccines can make you artistic.