IS is a compound function in Model 1, created by the combined activity of Ni->Se or "Ni in service to Se." IS has the same general attitudes as Si (I+S), but is coming from Ni-Se's metabolism. IS is the sub-primary function of the NiFe and NiTe types and is present in all Beta and Gamma types.
The IS compound is produced when Ni, as a worldview function, is used to link together Se's information, such that it's chained into a longer array of literal data. What results is a chain of detailed information points, which nonetheless exist as beads running across an Ni thematic thread, and which are representative of an Ni motif in a larger, convergent Ni tapestry. This differs from Si, which archives together datapoints anecdotally, arranged together by historical accident and in a modular fashion. By contrast, the IS compound composites a tangible substantiation of an Ni shape/form in the world, expressing itself discretely while never being disconnected from its convergence along Ni's isomorphisms.
The following are behaviors commonly manifested by Ni in service to Se.
When Ni's operation is put in service of Se, Ni goes towards recollecting all literal datasets that pertain to a specific context at hand. Its thematic web echoes back an array of details that pertain to the literal situation before them. However, due to the nature of Ni-Se data existing within a vortical structure, this process only touches upon data that is inside the isomorphic trendline of Ni. In this way, the literal array that is produced amounts to a trans-local motif being represented locally by means of examples. The IS compound can create exhaustive factual arrays of this sort, but the data is always exemplifying a non-local position. It's therefore tailored and shaped to complement the narrative of that motif, rather than being a standalone array of historical facts. Si, on the other hand, chronicles a situation in an as-is fashion, not situated within a larger trendline. For Si, history is not 'directed' down very structural and symbolic intersections --it just is. As such, when Si narrates stored information, it will inherit the chaotic and random nature of history, adding anecdotal tangents and factoids that were part of the whole historical situation, but which may not have served any thematic purpose.