textFormatRuns property

Runs of rich text applied to subsections of the cell.

Runs are only valid on user entered strings, not formulas, bools, or numbers. Properties of a run start at a specific index in the text and continue until the next run. Runs will inherit the properties of the cell unless explicitly changed. When writing, the new runs will overwrite any prior runs. When writing a new user_entered_value, previous runs are erased.