Behaviour class - a grouping of signs by where they occur in a text (openers, text-final markers, strict medial connectors, numerals...), derived from position statistics, not shape.
CISI - Corpus of Indus Seals and Inscriptions (Joshi & Parpola 1987-), the standard edition. Its numbering (M-nnn for Mohenjo-daro) is used by most digitisations.
Conditioning excess - how much of the uncertainty in one element is removed by its neighbour, above what the same corpus gives when shuffled, as a share of that element's entropy. Used for all cross-corpus comparisons because raw mutual information is upward-biased in small samples.
Determinative - in Egyptian, an unpronounced sign at the end of a word marking its category. Identified here distributionally (word-final, attaching to many unrelated words).
DK area, SD area, HR, VS... - excavation areas at Mohenjo-daro. DK and SD are Mackay's; HR, VS and the rest appear in Marshall's table.
First occurrence - the deduplication flag. Many inscriptions are near-duplicates; all analyses use one representative per group.
G-numbers (G740, G520...) - sign identifiers in the digitised corpus used here. Not a standard list: G740 is the "jar", G520 the "arrow".
Jar sign (G740) - the commonest text-final sign, ending about a third of texts and almost never starting one.
M77 - Mahadevan's 1977 corpus, The Indus Script: Texts, Concordance and Tables.
Minimal pair - two texts differing in exactly one position; used to test whether texts are built by varying one slot of a shared frame.
Phase estimate - a rough chronological band derived from level. Approximate; see the depth caveat in LIMITATIONS.
Reading direction - right to left, as the script runs. On an impression the reading order therefore runs from the right edge, so a text's ENDING appears at the left.
Register - here, the distinction between the main line of an inscription and the short formulaic second line found on about a fifth of them.
Type B, F, C, D... - Mackay's seal shapes. B is the square seal with a perforated boss (the classic animal seal); F is the rectangular inscription-only seal.