"Source Period Year" only allows Number

Summary:

We are building a file-based integration with columns including Year and Period. We are unable to define a "No Year" value in the file under the Year column.

Details:

Below is the file format haivng "No Year" as a value.

To read "No Year", we tried to define this in the Source Mapping which didn't work

But if we replace "No Year" with "2027" as below

And period mapping as

Then it works fine.

Question:

1. How can we update the configuration to run the integration based on "No Year" in the source file?
2. Does this mean we can't even define FY27 and FY28 in the source, as these are also not purely numeric?