/**
 * Chart / chartEx internal structure check.
 *
 * Classic charts (`xl/charts/chartN.xml`) must contain both `c:chart` and
 * `c:plotArea`. ChartEx charts must contain `cx:chart`, `cx:plotArea`
 * and at least one `cx:series`; series must carry `layoutId` and their
 * `dataId`/`axisId` back-references must resolve inside the chart.
 * `cx:externalData` nodes must refer to a declared relationship.
 *
 * In addition we catch five chartEx schema-violation patterns that
 * cause Excel 2016+ to drop the whole chartEx part with "Removed Part:
 * /xl/drawings/drawingN.xml (Drawing shape)":
 *
 *   - `<cx:series>` with more than one `<cx:dataId>` child
 *     (`CT_Series/dataId` has `maxOccurs="1"`; multi-dim series must
 *     use a single `<cx:data>` wrapper with multiple strDim/numDim).
 *   - `<cx:axisId>N</cx:axisId>`, `<cx:dataId>N</cx:dataId>`,
 *     `<cx:binCount>N</cx:binCount>`, `<cx:binSize>N</cx:binSize>`
 *     emitted as text content instead of `val="N"` attribute. The
 *     underlying types are `CT_UnsignedInteger`/`CT_Double`, which
 *     Excel's strict loader only accepts via the attribute form.
 *   - `<cx:auto/>` element anywhere in the chartEx. Auto binning is
 *     expressed by the ABSENCE of `binSize`/`binCount`, not a
 *     dedicated `<cx:auto/>` tag. The tag is schema-invalid.
 *   - `<cx:paretoLine>` child of `<cx:layoutPr>`. Not in the
 *     CT_SeriesLayoutProperties schema. A real pareto chart adds a
 *     second series with `layoutId="paretoLine"`.
 *   - `<cx:title>` with a direct `<cx:layout>` child. Title layout
 *     belongs in `extLst`-based extensions.
 */
import type { ValidationContext } from "./context.js";
export declare function checkChart(ctx: ValidationContext): void;