Final answer:
The data provided does not directly answer the question about when the 2020 4ID Green Book Standards were updated, as it only references a change in standards effective December 28, 2015, and does not mention the 2020 update.
Step-by-step explanation:
The question refers to the update of the 2020 4ID Green Book Standards, which are guidelines or regulations that have undergone revisions. However, the information provided mentions the final rule signed on October 1, 2015, and effective from December 28, 2015, which pertains to some environmental or operational standards and not specifically to the '2020 4ID Green Book Standards'. The data suggests that there were previous standards set in 2008 and that these 2008 03 standards are still effective in some areas. The transitioning to the current (2015) standards from the 2008 standards is noted as something that will occur with the implementation rule for the 2015 standards.