Julian year 4713 BC is -4712, because year 0 = 1 BC #1536
                
     Merged
            
            
          
  Add this suggestion to a batch that can be applied as a single commit.
  This suggestion is invalid because no changes were made to the code.
  Suggestions cannot be applied while the pull request is closed.
  Suggestions cannot be applied while viewing a subset of changes.
  Only one suggestion per line can be applied in a batch.
  Add this suggestion to a batch that can be applied as a single commit.
  Applying suggestions on deleted lines is not supported.
  You must change the existing code in this line in order to create a valid suggestion.
  Outdated suggestions cannot be applied.
  This suggestion has been applied or marked resolved.
  Suggestions cannot be applied from pending reviews.
  Suggestions cannot be applied on multi-line comments.
  Suggestions cannot be applied while the pull request is queued to merge.
  Suggestion cannot be applied right now. Please check back later.
  
    
  
    
Companion PR to (currently unmerged) swiftlang/swift-corelibs-foundation#5274
This is a minor comment-only fix. The minimum of the range (
-211845067200.0) does indeed represent Julian day 0 (proleptic Gregorian-4713-11-24 12:00:00 +0000= November 24, 4714 BC), but it is documented incorrectly as proleptic Julian-4713-01-01 12:00:00 +0000which is 4714 BC instead of the correct year -4712 = 4713 BC