How to import iif file invitem with G (GST) type tax only

I can import an invoice with multiple invitems no problem but the !SPL line only has "TAXABLE" as a tax column that is either Y or N.  Where when imported Y = S standard tax (both taxes applied) and N = E exempt (no taxes applied).

I need to be able to import an invitem that has tax type G (GST Only)

How do I do that.  I tied puting a G where the Y is and it errors on import that it's invalid.

Here is the inv item:

!SPL SPLID TRNSTYPE DATE ACCNT NAME CLASS AMOUNT DOCNUM MEMO CLEAR QNTY PRICE INVITEM TAXABLE EXTRA

SPL INVOICE 2019-11-19 Legal Fee Income -85.00 Court Registration N -1.0 85.00 Court Reg Y

Sample import with multiple invitems is attached