The document is a correction notice related to a previously published rule by the Pipeline and Hazardous Materials Safety Administration under the Transportation Department. It corrects a date error in rule document 2020-23353, originally published on December 21, 2020. Both occurrences of "January 20, 2021" on page 83366 are updated to "January 21, 2021" to reflect the correct date in the DATES section.
Simple Explanation
The document talks about a small mistake where someone wrote the wrong date—January 20, 2021—and it should actually be January 21, 2021. It's like fixing an error in a story to make sure everyone knows the right date.