This entire paragraph is incorrect. You do not imply your acceptance of the GPL by reading the source code. You do not have to accept the license at all. How

This entire paragraph is incorrect. You do not imply your acceptance of the GPL by reading the source code. You do not have to accept the license at all. However, if you do not accept the license, then you have no right to distribute the code. It is on conveyance (distribution) that the restrictions show up. There are absolutely no restrictions on what you can do if you do not distribute the code. That whole section in their documentation is just weird, to be honest. There is nothing in the BSD license that requires you to sign additional legal documentation either. The fossil project requires copyright assignment to include your code in the project (many FSF projects require the same thing with their projects for similar reasons). They should just delete that section so that they don't look like they don't know what they are talking about. Edit: They could rewrite the section to say that by distributing the code you have implicitly agreed to the license. This is more or less true. The license actually hinges on the fact that you never have to agree, but that if you don't agree then you only that the rights assigned to you by copyright (see section 9 of the GPL v3). The bit that's weird is that there is absolutely no difference with the BSD license -- you don't have to agree, but if you don't, then you don't have a license. The only real difference is that the BSD license doesn't explicitly say so. At first I thought they were trying to make a political point, but the more I look at it, the more I think they just want to justify requiring copyright assignment. The obvious question is "Why don't all those GPL projects require it?" So they came up with something plausible, but completely incorrect.