What intrinsic function is used to refer to a specific value in a comma-delimited list?

The intrinsic function used to refer to a specific value in a comma-delimited list is Fn::Select. This function allows you to retrieve an item from a zero-based index within a list of values. For example, if you have a list of allowed instance types, using Fn::Select with the appropriate index enables you to specify which instance type to use in your resource configuration.

Fn::Select is particularly useful when combined with other functions, such as Fn::Split, which can break a single string into a list based on a delimiter (like a comma). Once the string is split into a list, Fn::Select can then be employed to pull out a specific element from that generated list.

This ability to reference specific elements makes Fn::Select essential for efficient CloudFormation templates where dynamic values or configurations might be required based on the indices of the elements in a predefined list.