For us here, we have two restrictions. 1. Not using company resources or time to work on it. Meaning do it on your own time.
2. It does not directly compete with the company / it's contracts. Meaning not doing work for a rival company for something they are/could compete on. However the SDK doesn't fall into that. Just as a third optional thing I do is write everything from scratch that gets put into the SDK. Many times I may have already solved an issue locally and I don't want the code donated to be the same. Which also accounts for some strange naming/placement in the end :P -Mark