GPL exception ???

[Sven Luther <sven.luther@wanadoo.fr>]

Hello, ...

I came on a program that is distributed under the GPL with the addition
of the following exception :

  Derivative works must not remove the original author's copyright
  notices, name or comments from source code and documentation. Doing
  so will violate the license.

I had the impression that the GPL already provides for forcing the
original copyright notice and author name to stay in the modified work,
but could not pinpoint the exact place of it.

Furthermore, the obligation to not remove comments from the source code
seems to me not compatible with the GPL, but i may be wrong in this.

Could someone more knowledgeable look into this and give me his advice ?

Friendly,

Sven Luther