Usually every post is assigned its place in a feed in accordance with its timestamp. But it is absolutely possible that two posts will have the same timestamp, so the position becomes ambiguous. To make the feed working properly, we need to be able to fix the position and order of posts and specify a position in the feed to within a particular post.
To achieve this goal, every post is assigned a moment, that is calculated as follows:
moment = timestamp * 100 + seq
seq here is an arbitrary number from 0 to 99 that is chosen by the
node to make the resulting value unique.
Moments larger or equal to 9⋅1015 are assigned to “pinned” posts.