Can I call my program "Open Source" even if I don't use an approved license?
Please don't do that. If you call it "Open Source" without using an approved license, you will confuse people. This is not merely a theoretical concern — we have seen this confusion happen in the past, and it's part of the reason we have a formal license approval process. See also our page on license proliferation for why this is a problem.
Is <SOME LICENSE> an Open Source license, even if it is not listed on your web site?
In general, no. We run all licenses through an approval process to provide an accepted standard on which licenses are Open Source, and we list the approved ones. Be dubious of claimed Open Source-ness for licenses that haven't gone through the process. See also the license proliferation page for why this matters so much.
Can I call my program "Open Source" even if I don't use an approved license?
Please don't do that. If you call it "Open Source" without using an approved license, you will confuse people. This is not merely a theoretical concern — we have seen this confusion happen in the past, and it's part of the reason we have a formal license approval process. See also our page on license proliferation for why this is a problem.
Is <SOME LICENSE> an Open Source license, even if it is not listed on your web site?
In general, no. We run all licenses through an approval process to provide an accepted standard on which licenses are Open Source, and we list the approved ones. Be dubious of claimed Open Source-ness for licenses that haven't gone through the process. See also the license proliferation page for why this matters so much.