To understand this property, think of a LineSeries Chart: when 3 data points form a "V" shape, this property will specify how the bottom part of the "V" looks.
A list of the available options can be found in the JoinType enumeration.
The default value is Round.
Target Platforms: Windows 11, Windows 10, Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2