AWS SDK for .NET Documentation
NonKeyAttributes Property
AmazonAmazon.DynamoDBv2.ModelProjectionNonKeyAttributes Did this page help you?   Yes   No    Tell us about it...
Represents the non-key attribute names which will be projected into the index. For local secondary indexes, the total count of NonKeyAttributes summed across all of the local secondary indexes, must not exceed 20. If you project the same attribute into two different indexes, this counts as two distinct attributes when determining the total.

Constraints:

Length
1 - 20

Declaration Syntax
C#
public List<string> NonKeyAttributes { get; set; }

Assembly: AWSSDK (Module: AWSSDK) Version: 1.5.60.0 (1.5.60.0)