pg_timezone_names

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/9.1/static/view-pg-timezone-names.html
Description:

We are exporting data from postgres into another "all in one" data store,
and i had a quick question regarding the time offsets.  The UTC_OFFSET, does
it change when IS_DST is true/false?  Or do I need to take the UTC_OFFSET
interval and then possibly add 1 more if IS_DST is true?  Example: 1/1/2018
not in DST, interval says -10.  On 3/1/2018, IS_DST turns to TRUE.  Will the
interval now say -9, or do i need to take the -10 and substract 1 to get to
-9?