dax

dax-lib-install

Use when a DAX UDF already published on daxlib.org (found via the dax-lib index) needs to be actually installed against a real model — not just documented. Fetches the real function body from the daxlib/daxlib registry, checks its declared license, installs it (modeling MCP if connected, else a direct TMDL edit), runs a real DAX query to confirm it executes, and leaves it attributed on the function itself (author, license, source URL) so it is never mistaken for original work. Triggers on "install this UDF", "bring in the daxlib function", "add TimeSeries.MovingAverage to my model", "vendor this DAX package".

dax-lib

Use when looking for an EXISTING published DAX user-defined function before writing one — moving averages, format strings, SVG visuals, KPI/variance, RFM or ABC classification, unit conversion, model audit/metadata, sample data, time intelligence. Offline index of the DAX Lib registry (daxlib.org) — what exists, who wrote it, and where to get it. Triggers on "is there a UDF for", "find an existing DAX function", "ready-made", "already exists", "daxlib", "DAX package".

dax-reference

Use when you need to know what a built-in DAX function does, its exact signature, what it returns, whether it is legal in a measure, a calculated column, a calculated table or a visual calculation, whether Microsoft discourages it, or which of several similar functions to reach for — and equally for the DAX language itself when no single function is in question, such as evaluation context, context transition, filter and row context, the query statements EVALUATE, DEFINE, MEASURE, ORDER BY and START AT, operators, data types, BLANK semantics, variables with VAR, and Microsoft's own best-practice guidance. The canonical reference for DAX. Triggers on "what does X do in DAX", "DAX function signature", "which DAX function", "difference between", "is X deprecated", "can I use X in a calculated column", "does X work in a measure", "what is evaluation context", "context transition", "DAX query syntax", "EVALUATE statement", "what does BLANK mean in DAX", "DAX operators", "DAX best practice".

dax-udf-authoring

Use when AUTHORING your own DAX user-defined function — the mechanics of writing a FUNCTION — declaring parameter types (Scalar, AnyRef, ColumnRef, MeasureRef, CalendarRef), VAL vs EXPR evaluation, TABLEOF/NAMEOF, optional parameters and defaults, dot-notation naming, GA limitations and parser red-underline bugs. Not for finding an existing one (that is dax-lib) nor for what a built-in does (that is dax-reference). Triggers on "write a DAX UDF", "define a DAX FUNCTION", "ANYREF", "VAL vs EXPR", "TABLEOF", "optional parameter in a UDF".

dax-window-functions

Use when writing a DAX window function — WINDOW, OFFSET, INDEX, RANK, ROWNUMBER, MOVINGAVERAGE, RUNNINGSUM with ORDERBY/PARTITIONBY/MATCHBY — for rolling and trailing averages, running totals, prior-row or prior-year comparisons, or ranking within a partition. Covers ABS vs REL positioning, the ALLSELECTED relation default that silently returns blanks, and MATCHBY for fact tables. Triggers on "rolling average", "running total", "trailing N", "OFFSET returns blank", "ABS vs REL", "PARTITIONBY".