\input eplain

{\center foo
bar
}

% Changing \parfillskip is OK, since the macros reset it.
%\parfillskip = .75\hsize plus .06\hsize minus .75\hsize
\loggingall

Pre-text.  These should be flush left:
{\flushleft
Here are a few
lines that we are
\vadjust{\bigskip}going to take {\it literally}. (with vadjusted space now)
And a couple more
of them.}

Now we're back to normal.
Now we're back to normal.
Now we're back to normal.
Pre-text.  These should be flush right:

{\it \flushright
Here are a few italic
lines that we are
\vadjust{\bigskip}going to take literally.
And a couple more
of {\bf them.}

In fact, let's do two paragraphs,
this is so much fun.  No, let's make it three.

   For Dan
   ---{\bf k.b.}
}

Now we're back to normal. 
Now we're back to normal. 
Now we're back to normal. 
These should be centered.

{\center
Here are a few
lines that we are
\vadjust{\bigskip}going to take literally.
And a couple more
of them.}

Some centered paragraphs:
{\center
  Here is the first paragraph.
  
  Here is the second.
  
  Here is the third.
}

Now we're back to normal. 
Now we're back to normal. 
Now we're back to normal. 
These should be flush left again (two groups):

{\flushleft
  Here is the first paragraph.
  
  Here is the second.
}

\blanklineskipamount = -.8\baselineskip
{\flushleft
  Here is the first paragraph.
  
  Here is the second.
  
  Here is the third
}

We changed the amount of space between the paragraphs in the second
group so it was less than a full blank line.  Did you notice?

\scrollmode

{\message{Now comes a mysterious error.} \center on first line---what happens?
centered
}

\def\title{\begingroup\center}
\def\endtitle{\endgroup}

\title
this should be centered
by virtue of a macro
\endtitle

Back to normal.

{\center
centered
\message{Now there should be an error:}%
\flushleft % error
}

\bye
