the following; undermentioned; at left
Used in formal or vertical writing to refer to text that follows (or appears to the left in traditional layout). In modern horizontal text, it still means 'the following'.
We will inform you as follows.
As stated below, we will change the schedule.
Details are as follows.
For details, see below.
左記 refers to text that follows (traditionally to the left), while 右記 refers to text already mentioned (traditionally to the right).
From 左 (left) + 記 (record/writing). In traditional vertical writing, text that follows appears to the left of the current position, hence 'the following'.