Represents the "Subtype" entry of the 3d lighting scheme dictionary object.

It is a required entry defined as part of the PDF 1.0 specification.

It contains a string representing a PDF name object.

This item may take one of the following valid values:.

• Artwork
• None
• White
• Day
• Night
• Hard
• Primary
• Blue
• Red
• Cube
• CAD
• Headlamp

For definitive details see:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 309, page 530.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 320, page 662.