[1] Standard master - ECMA-48_5th_edition_june_1991.pdf, 1/16/2021, 9:56:56 AM, 5/14/2022, 5:47:11 AM https://www.ecma-international.org/wp-content/uploads/ECMA-48_5th_edition_june_1991.pdf#page=67
[2] GB 8565.3-88
Google search: PTX