Alfred M. Szmidt wrote:
There is no doubt that free software needs free documentation, even FSF says this. If so, why does FSF allow restrictions to modifications of documentation (using FDL) that does not allow for software?
Because such restrictions make sense, you don't need the right to modify my thoughts about why I wrote the book, or to whom I dedicated the book.
As this seems to be a center of your argument, can you back this up (to use your favourite expression)?
Why should a dedication of a manual deserve different restrictions than one of a computer program?
You might say because a computer program is functional. But so is the main part of a manual (as has been pointed out to you). So the question can be reformulated as: Why must a computer program be 100% functional, and a manual doesn't have to be?
Technical differences don't really apply in most cases. An invariant part could be included in most kinds of programs without hindering their normal performance, such as being shown by a particular option or menu item, or even on a startup screen (that a user who doesn't want to read it can click through, just like a manual reader(*) can skip over the pages with the invariant sections).
(*) To avoid any misunderstanding: By "manual reader" I mean a reader of a manual, rather than someone who reads with his hands. This might be clear from context, but you never know ...
Secondly, the question whether someone should be allowed to modify your expression (or your "thoughts", as you prefer to call it), is beside the point. Even a GPL work can be accompanied by an unmodifiable text (GPL, paragraph 2, last sentence). There are two main differences compared to an FDL work with invariant sections:
1. The former case would be two different licenses (GPL plus something else), the latter case would be "all FDL". But that's really just naming, as the FDL already gives two rather different sets of rights for the main part and secondary sections.
2. In the FDL case, the invariant sections are tied to the main part. You can't reuse parts of the latter without including the former. In the GPL+x case, you can. That's IMHO the main difference, so I'd like to know why you think having to include them is a good thing.
Frank