Help with "out of order" plotting

[Corey Stup]

I'd like to convert an existing markup based format specification and
possibly use lout to render Postscript from it.

Our current stream allows the following, where sequences:
!xy = (escape character) (lines to advance, 0=stay on current line)
(tab stop, A=far left, Z=far right)

So, the stream can output:
!1ZFarRightData!0AFarLeftDAta

Which would say:
Move down a line, and, plotting from the far right, render "Far RIght
Data".   Next, stay on the same line, and plotting from the far left,
render "Far Left Data".   The output would be:

Left                 Page width                    Right
<------------------------------------------------------>
FarLeftDAta                                 FarRightData

To get more tricky, our current plotter will also do the following:
Given a stream:
!0ZRight Data Justified!1ALarge String of Characters that would run
together and just keep on going, no matter what.

It would plot:
<----------------------------------------------------->
Large String of Characters that    Right Data Justified
would run together and just keep on going, no matter 
what.

Since the data on the right side "took position" first, it wraps the
remaining text to be plotted around it, breaking on words.

Looking at the manual, I didn't find where this type of positioning
was obvious.  It seems that since lout is capable of keeping track of
where each text blob object is, it could wrap around previous text on
a given line.  

Could someone point out if I'm missing anything or some examples to
get me going?    

Thanks in advance!