What determines the order of frequent poster icons in the topic list?

Hmmm… If one looks at the Api documentation topic none of the explanations seem to map onto it (or I am overlooking something):

Topic overview:

Banner (within topic):

Post order: both when I start from the beginning and reverse from the end; I can not seem to reverse-engineer it to any of the explanations (not even when grouping by amounts of post and chronologically ordering them within those groups).

Am I overlooking something? Is anyone able map his/her explanation on that (or another) existing topic, in order to enlighten me?

The first/far-left (OP) and last/far-right (LP) ones are clear, but the three in the middle are not. They are usually the top posters, but esp. the presentation-order still confuses me (I do not seem to recognize a chronological order, nor a descending based on their relative amount of post).

e.g. - the Api documentation topic - how come pjv is preferred over Jared_Needell in that case?