BorderType API in JavaScript (ES5) Chart API control

Defines the border type for multi level labels. They are:

• Rectangle - A rectangular border around the labels.
• Brace - A brace-style border around the labels.
• WithoutBorder - No border around the labels.
• WithoutTopBorder - No top border around the labels.
• WithoutTopandBottomBorder - No top and bottom borders around the labels.
• CurlyBrace - A curly brace-style border around the labels.
• Rectangle
• Brace
• WithoutBorder
• WithoutTopBorder
• WithoutTopandBottomBorder
• CurlyBrace