Determines which pixel values will be taken under consideration in processing in surface edge detection related operations.

Values of this enumeration:

• High - Stripe with high Z values.
• Low - Stripe with low Z values.
• AnyLowHigh - Stripe with high or low Z values.
• Invalid - Stripe with no Z values.
• Valid - Stripe with existing Z values.
• AnyValidInvalid - Stripe with no Z values or all existing Z values.