How does pasting from Excel work here?
Select a single column of cells in Excel, copy it, and paste into the text box. Excel copies a column as one value per line, which is exactly the format this tool expects: one code per row, no reformatting needed on your end.
What if some rows are wrong?
They’re skipped and listed separately rather than silently dropped or breaking the whole batch. Fix the flagged rows in Excel, copy the column again, and paste to regenerate.