Preserved

PreservedPart

_interface

A package part the model does not interpret, captured verbatim so a round-trip re-emits it intact. bytes are the raw part contents, contentType how the source package declared it, and rels its outbound relationships (empty when the part references nothing). The writer re-numbers the part to a fresh, collision-proof path and rewires rels accordingly, but never touches bytes.

interface PreservedPart {
  readonly path: string;
  readonly contentType: string;
  readonly bytes: Uint8Array;
  readonly rels: readonly PreservedRelationship[];
}

---

PreservedRelationship

_interface

One outbound relationship of a PreservedPart: the id it carries inside its own rels part, the relationship Type URI, and its target. An internal relationship's targetPath is the resolved package path of the part it points at (the writer re-numbers and rewires it); an external relationship's targetPath is the raw Target verbatim (a linked workbook's path or URL). It is outside the package, so it is emitted unchanged with TargetMode="External" and never remapped. Preserving external relationships is what keeps an externalLink part's pointer to its source workbook alive, so a round-trip does not orphan the [n] external references formulas resolve through.

interface PreservedRelationship {
  readonly id: string;
  readonly type: string;
  readonly targetPath: string;
  readonly external?: boolean;
}

---

PreservedRootReference

_interface

A package-root reference to content the model does not model, wired from the package's own _rels/.rels rather than the workbook part's rels: the ribbon-customisation parts (customUI/customUI14.xml), custom document properties (docProps/custom.xml), a thumbnail, and anything else hung off the root. The writer regenerates the root rels for the parts it models (workbook, core/app properties), so these would be dropped unless captured here and re-declared. relType is the relationship Type URI to re-emit, entryPath the part it targets (kept at its original path, since the writer generates nothing of these kinds to collide with), and parts the transitive closure the reference reaches.

interface PreservedRootReference {
  readonly relType: string;
  readonly entryPath: string;
  readonly parts: readonly PreservedPart[];
}

---

PreservedWorksheetReference

_interface

A worksheet-level reference to package content the model does not model, preserved verbatim across a round-trip instead of being silently dropped. element is the worksheet child that wires the reference (<drawing> for a vector-shape drawing, <legacyDrawingHF> for a header/footer image), or undefined when the sheet wires it by relationship alone (a pivot table or slicer Excel discovers by scanning the sheet's rels, with no worksheet child pointing at it). relType is the relationship Type URI to re-emit; entryPath is the part it points at; parts is the transitive closure of parts that reference reaches (the entry included), each re-emitted with its relationships rewired.

interface PreservedWorksheetReference {
  readonly element: 'drawing' | 'legacyDrawingHF' | undefined;
  readonly relType: string;
  readonly entryPath: string;
  readonly parts: readonly PreservedPart[];
}