.
Tunnelblick itself will append either "-b" or "-s", depending on whether it is a beta or stable version, before making the request. ("-b" is used when "beta" is contained within the Info.plist's
CFBundleShortVersionString, otherwise "-s" is used.)
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As of 6.0beta01, Tunnelblick's appcast can now be a v3 (e.g. "
https://xxxx.xxx/appcast-v3.rss"), which can contain multiple <item>s and adds two additional optional tests:
maximumSystemVersion and
architectures, to facilitate a future transition to versions of macOS and/or Xcode that support only Apple Silicon.
architectures is a space-separated list of processor architectures including either "x86_64" or "arm64" or both. If
maximumSystemVersion or
architectures are omitted, no corresponding test is performed.
Note that v3 appcasts are still signed with v2 signatures.
Tunnelblick's 6.0beta03 appcasts contain two <item>s, one for x86_64, one for arm64. They are identical except for "architecture". You can examine it with