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I was checking the license compatibility of some open source software and I found out that sometimes software is released with a weird license like GPLv2+ / LGPLv2.1+. I'm not sure about the "plus" meaning. Does it mean "this and newer" version?

For example:

Finally, this nomenclature is also on wikipedia

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Does it mean "this and newer" version?

Yes. The + symbol is used to informally indicate that the license is the specified version or any later version. It is so much shorter than the phrase "or any later version", although that is what you should still use in the official license indications.

This usage is only common with the GPL suite of licenses, because those licenses do support the notion of newer versions coming out, but they don't have an automatic license-upgrade. Instead, it is left to the original authors to decide if license upgrades are supported or not.

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  • So if I remove "or any later version" statement from my header notice (GPLv2), do I prevent to use my source code in GPLv3 projects? Mar 31 at 12:56
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    @fabiuz7 Yes, plain GPLv2 and GPLv3 are incompatible, so they cannot be applied to different parts of the same work under copyright (GPL requires that the work as a whole be under that version of the GPL, and it cannot be v2 and v3 simultaneously). If your work is GPLv2-or-later then it works because your GPLv2+ grant turns into GPLv3, making it compatible.
    – apsillers
    Mar 31 at 13:42
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You are looking at the wrong thing to determine what license applies to software: what you've linked are statements by GoPro and Nanit where they make some assertions. It doesn't matter if GoPro say libavahi-common3 is released under the "GPL v2", "GPL v2+" or "Fuzzy Aliens From Space License", because they are not the copyright holders of libavahi1.

If you want to know what license(s) are applicable to libavahi, you should look at the Avahi source.

1. Well, it matters to GoPro because they will be in trouble if they do not comply with the terms of the license but it doesn't matter to you.
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    While this answer isn't wrong by any means, I think using+ to mean "or later" with respect to a GPL version is very common, and was even codified in (now deprecated) SPDX identifiers. While GoPro's and Nanit's assertions indeed aren't binding, I think the OP wants to understand what the assertions even are in the first place.
    – apsillers
    Mar 31 at 14:15

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