This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
A modality entry records one of the three ranks Hellenistic astrology gives the twelve houses by their position relative to the four angles of a chart, angular, succedent and cadent, a threefold classification Paulus Alexandrinus' fourth century handbook sets out as part of its own systematic introduction to the whole discipline, alongside the parallel classification of the zodiac signs into cardinal, fixed and mutable.
An entry records which four houses a modality covers, first, fourth, seventh and tenth for angular; second, fifth, eighth and eleventh for succedent; third, sixth, ninth and twelfth for cadent, and the specific strength or weakness of effect Hellenistic tradition assigns a planet standing in a house of that rank, since the houses were not treated as equal in force.
Paulus' handbook was written as a teaching text, an introduction meant to give a student the whole working system in compact form, so an entry can draw on it for the documented basic scheme itself, the names, the groupings and the plain statement of relative strength, distinct from the more elaborate technical debate later astrological writers built on top of that same basic threefold division.
An entry also keeps a modality's positional rank distinct from a planet's dignity within the sign it occupies, since Paulus' own text treats house position and sign based strength as two separate measures that a chart reading combines rather than substitutes one for the other.