Hika Shop: changing text displayed in forms - ex: changing Product Code to ISBN

-- HikaShop version -- : 3.0.1
-- Joomla version -- : 3.6
-- PHP version -- : 7
-- Browser(s) name and version -- : any

just a tip on how to change the text displayed in a form such as components->products-new
For example, if you want to change text of "Product code" & the tooltip "Product code (SKU)" to ISBN
(see attached screen capture from:
/administrator/index.php?option=com_hikashop&ctrl=product
modify HIKA_PRODUCT_CODE and PRODUCT_CODE_SKU in this file:
/language/en-GB/en-GB.com_hikashop_copy.ini
as follows:
;the following line is replaced by the one below it 4-20-17
;this is the tooltip
OLD_PRODUCT_CODE_SKU="Product code (SKU)"
PRODUCT_CODE_SKU="ISBN"

;the following line is replaced by the one below it 4-20-17
;this is the text displayed in the form
OLD_HIKA_PRODUCT_CODE="Product code"
HIKA_PRODUCT_CODE="ISBN"