must send modifications license acceptable?

[Rahul Sundaram]

Patrice Dumas wrote:
> Hello,
> 
> In TeX Live there are at least 2 licenses with the obligation to send
> modifications:
>  *   This is dvips, a freely redistributable PostScript driver
>  *   for dvi files.  It is (C) Copyright 1986-2004 by Tomas Rokicki.
>  *   You may modify and use this program to your heart's content,
>  *   so long as you send modifications to Tomas Rokicki.  It can
>  *   be included in any distribution, commercial or otherwise, so
>  *   long as the banner string defined below is not modified (except
>  *   for the version number) and this banner is printed on program
>  *   invocation, or can be printed on program invocation with the -?
>  *   option.
> 
> For makeindex there is a rather classical license with:
> "All modified versions should be reported back to the author."

A requirement to send modifications to anybody is non-free. A request to 
do so as in the Academic Free License is not.

Rahul