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    "The Result Card includes an engine-linked figure of X(z) on the real ROC (pole at |z|=|a|) or a stem of x[n] (at most 16 indices). Same table as REST/MCP.",
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    {
      "title": "ISO 80000-2:2019 Quantities and units — Mathematics",
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      "kind": "standard",
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      "supports": "The z-transform, its relation to the discrete-time Fourier transform, inverse transform and region of convergence. A rational expression alone does not identify the time sequence without its ROC. Mathematical reference only; not validation or endorsement of this implementation.",
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      "publisher": "Massachusetts Institute of Technology"
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