[dvd-discuss] Interpreting the Jaszi graph

[John Schulien <jms(at)johns.cc.uic.edu>]

> Peter Jaszi put together a nice graphic of the incredible shrinking
public 
> domain, as compared to the growth it would have had if copyrights had 
> expired as planned ...

Here's the description from the PDF:

| Although the number of creators and creations has grown
| over time, every term extension has created a period of "zero
| growth" in the public domain as shown in chart i.
 
<http://cyber.law.harvard.edu/openlaw/eldredvashcroft/pubdomain.html>

I'm completely baffled by this graphic.

o What exactly does the Y axis represent?

o What is the meaning of the purple area?
  The grey area?  Is this the number of 
  works?  Percentage of works?  Something
  else?

o Why doess the graph appear linear, when 
  the growth of published works has been 
  exponential?

o Prior to 1978, any work published without
  proper copyright notice immediately entered 
  the public domain.  How does this fit in 
  to the "zero growth" areas of the graph?

o During the "zero growth" periods, 1831, 
  1909, 1962, many works, entered the public 
  domain due to failure to renew copyright.  
  Are those not represented on the chart, or 
  is the number of unrenewed copyrights 
  negligable?  I thought that it was the 
  other way around -- that only a very small 
  percentage of copyrighted works had their 
  copyright renewed.

o Note that with the renewal requirement
  removed, and automatic copyright protection
  for all works, we ARE now in a situation
  of zero growth of the public domain --
  but this is only since 1976.

o If the public domain was growing at a large
  "Y" value in 1831, then drops to zero, why
  does it start at zero 14 years later when
  copyright expirations resume, instead of 
  picking up where it left off?

Does anyone have a better understanding of 
this graph?