Errata & rulings

What we got wrong, and what we decided

A printed deck cannot be patched. This page is where corrections to the cards are recorded, together with rulings on rules questions that came up in play and were not settled by the Guide.

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An entry here overrides the printed card and the Guide. If a card's text and an erratum disagree, the erratum wins. Cite it by its number in an oral evaluation and you are on solid ground. Entries are listed newest first and are never deleted, for a given version of the cards.

Entries

Corrections and rulings

ERR-002 · 16 September 2026 v1.0 Card Open

Truncated descriptions in Transform cards

D-01 Aggregate; D-02 Bin; D-03 Rank; D-04 Fit/Model

Issue.Changes due to last-minute constraints when printing led to truncated descriptions in the Transform cards.

Ruling.Here are the complete texts for those cads:
D-01: Collapse a collection of values into a single summary statistic per group. Its output is itself an attribute — usable wherever an attribute is: a Channel, a Layout, or a Task's required port.
D-02: Discretise a continuous variable into N equal-width intervals. Its output is itself an attribute — usable wherever an attribute is: a Channel, a Layout, or a Task's required port.
D-03: Convert a quantitative variable into ordinal rank position. Its output is itself an attribute — usable wherever an attribute is: a Channel, a Layout, or a Task's required port.
D-04: Fit a statistical model to data, producing fitted values plus an uncertainty band. Its output is itself an attribute — usable wherever an attribute is: a Channel, a Layout, or a Task's required port.

ERR-001 · 26 August 2026 v1.0 Card Open

Calendar Heatmap lists two Position top ports when only one is needed

Q-36 Calendar Heatmap

Issue. The printed card shows two Position top ports. This would need two different attributes mapped to position. However, the most common use case for a calendar heatmap is to show a single categorical variable across time, so only one Position port is needed, corresponding to the temporal attribute. The fact that the heatmap may have a height and and width is an artifact of the layout that will try to match weeks, months, etc. in a calendar shape, but ultimately the position of each cell is determined by its temporal value only.

Ruling. Treat Q-36 as having a single Position top port.

Q-36 Calendar Heatmap technique card