We have a single ANTLR v3 contributors file in the repository that contains the contributors license. Anyone that wants to be a contributor, can simply fork antlr/antlr3 from github, add their name to "sign", commit, send a pull request and then they are in the system. Any future pull requests can be merged with a quick check on their name. The contributors file can also be augmented with their signoff him during the first pull request.
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