{{quote-book|en|author=Daniel Pellicer|coauthors=Egon Schulte|chapter=Polygonal Complexes and Graphs for Crystallographic Groups|editors=Robert Connelly; Asia Ivić Weiss; Walter Whiteley|title=Rigidity and Symmetry|location=New York, N.Y.|publisher=Springer|year=2014|page=331|isbn=978-1-4939-0781-6|passage=There are exactly 12 regular apeirohedra that in some sense are reducible and have components that are regular figures of dimensions 1 and 2. These apeirohedra are blends of a planar regular apeirohedron, and a line segment { } or linear apeirogon {∞}. This explains why there are 12 = 6·2 blended (or non-pure) apeirohedra. For example, the blend of the standard square tessellation {4,4} and the infinite apeirogon {∞}, denoted {4,4}#{∞}, is an apeirohedron whose faces are helical apeirogons (over squares), rising above the squares of {4,4}, such that 4 meet at each vertex; the orthogonal projections of {4,4}#{∞} onto their component subspaces recover the original components, the square tessellation and the linear apeirogon.}}

Drop-ins can and often do happen accidentally. Sometimes you're so focussed on your take-off that you just don't see the other rider.

Thus on some silver swan or tim'rous hare / Jove's bird comes sowsing down from upper air

That a bit too much to ask of me for I am not knowledgable in electronics enough to undertake such a project. Besides, I don't own a 390 or 392. There is a mod for the DX398/909 that speeds up the AGC. The modster's name is Ingo. Ingo are you listening and do you own a DX390?