How to include amount ranges for Credit Memo's in the Manage Payables Workflow Rules spreadsheet?

The organization I am working for requires approval rules dependend on the amount ranges for Invoices and similarly credit memo's. The amounts set through the spreadsheet upload are correctly working for the invoices but for the credit memo's (negative amounts) the approval workflows are not generated as expected.

Except for a very limited documentation the supported operators in Manage Workflow Rules Using a Spreadsheet (oracle.com) and a outdated source (Document Display (oracle.com)) on the use of negative amounts (pre-spreadsheet upload functionality) there seems to be no documentation on the matter.

The question is: how to include (negative) amount ranges for Credit Memo's in the Manage Payables workflow rules spreadsheet?