If you have to sign a copyright assignment statement, I'd think you'd be required to by the project (such as for GNU projects). But even if you don't assign your copyright to the project, I have a hard time understanding what using a pseudonym would do for you.
If your employer owns anything you create (like most businesses in the USA), then even if you submit under a pseudonym, once the employer finds out what name(s) you're using, they still own the copyright. You just make it harder and more annoying for them to find out that it's you.
I can understand if you're just writing a single bug report or sending a one-off email to a mailing list asking a question, sure, using a pseudonym is probably fine if you're worried about spam. But if you're actually contributing to the project (code, documentation, specs, marketing, etc), using your real name is the only way to go.
Also, if you put on your resume that you contribute to an open source project, I'd go check that out. If I can't find your name anywhere, I'm going to assume you're stretching the truth on your resume, probably in other places too.
There are limitations but frankly the line isn't clear as I would like it to be. My last job said anything I create using the tools provided to my (my laptop) could be subject to their ownership. My newest company goes a step further and says anything I create in my spare time becomes theirs. Their actual statement was, "Let's say you create the next facebook. Then that's our property." Of course after explaining to them that I was "helping" a friend build a specific web site they said that wouldn't be included as it is in another business sector than they function in. The odd thing is that facebook is not in their sector either. So again, my main complaint is that the line isn't as clear as I'd like it to be for my tastes.
In the US employers put a bunch of crap about how they own everything you do in their employment contract, but so far as I know they lack teeth. Mostly it is anything they may have contributed to, so company time, company materials, company information, etc. Where I work they have boiled it down to don't compete with us, don't do business with us, and don't use our stuff for your business.
In California and Illinois it may not necessarily be true due to laws those states have passed, but in most other states, it generally is. I live in New York state.
My contract states: "I will promptly notify <employer> of all inventions, discoveries, computer programs and systems, works of authorship, improvements, and developments, which I may produce during my employment with <employer>, and I assign my right, title, and interest to <employer> in such inventions, discoveries, computer programs and systems, works of authorship, improvements and developments."
There's other paragraphs roughly stating that if I notify upper management of my work done outside of business the company engages in or plans to engage in, upper management may provide me a written exemption for those specific works. But they do _NOT_ have to provide this to me, even if I ask nicely. I personally do not know anyone at my company who has ever gotten an exemption.
This is not true universally, regardless of what contracts you sign.
For instance, in California you have section 2870 of the Labor Code:
Any provision in an employment agreement which provides
that an employee shall assign, or offer to assign, any of his or her
rights in an invention to his or her employer shall not apply to an
invention that the employee developed entirely on his or her own time
without using the employer's equipment, supplies, facilities, or
trade secret information...
To be clear, this is what happens when you choose to sign an agreement that assigns all your inventions to your employer. It's not the default, and it can be worked around with little fanfare. If you're working on projects that are closely related to your employer's business, they want to own it. Otherwise, even big companies can be surprisingly lenient. But, yes, they typically ask for everything. It's just simpler (for them).
Big corporations are a lot more likely to do this. Smaller companies and startups (like where I am right now) are much more likely to just open source stuff that isn't core business logic.
An employer might not own anything we create in our free time, or there might not be an employer at all.
And if I put that I worked on a project under a pen name on a resume then I would include the name I worked under, accepting that it is probably not that anonymous anymore.
If you have to sign a copyright assignment statement, I'd think you'd be required to by the project (such as for GNU projects). But even if you don't assign your copyright to the project, I have a hard time understanding what using a pseudonym would do for you.
If your employer owns anything you create (like most businesses in the USA), then even if you submit under a pseudonym, once the employer finds out what name(s) you're using, they still own the copyright. You just make it harder and more annoying for them to find out that it's you.
I can understand if you're just writing a single bug report or sending a one-off email to a mailing list asking a question, sure, using a pseudonym is probably fine if you're worried about spam. But if you're actually contributing to the project (code, documentation, specs, marketing, etc), using your real name is the only way to go.
Also, if you put on your resume that you contribute to an open source project, I'd go check that out. If I can't find your name anywhere, I'm going to assume you're stretching the truth on your resume, probably in other places too.