Apple introduced support for Signposts in the unified log in High Sierra. Not only are they unavailable in macOS Sierra, but using the
log command with the option to fetch Signposts in 10.12 results in an error.
Although in all other respects my free log browser Ulbow is compatible with Sierra, if you enable its option to Get Signposts when running on Sierra, the
log command used will return an error. Ulbow version 1.3 fixes this: when running on Sierra, not only does it not attempt to use that option, but the two menu commands which handle Signposts are now removed.
Even if you don’t normally run Sierra, I recommend all Ulbow users to update to this new version, in case they use their copy on 10.12, and because the app has now been built with the latest SDK.
Thanks to EcleX for reporting this bug.