CellMerge
CellMerge =
"start"|"middle"|"end"
Defined in: src/core/document-model/types.ts:588
Resolved position of a cell in a vertical merge group (ECMA-376 §17.4.85
vMerge markers are resolved by the reader): start opens a group that at
least one cell continues, middle / end are continuations; undefined =
not merged. Continuation cells stay in their rows (they hold the column
slot); writers that need an HTML-style rowSpan can derive it by counting a
start’s middle/end run downwards.