The data validation rule should have values for formula1 and formula2 elements, which define the start and end values for a range to validate between. When such values are missing, a NullReferenceException is thrown on import and the document cannot be imported.
When the worksheet contains many formulas which use large ranges (e.g. covering 50000 cells) as arguments and these formulas have to be calculated, this causes OutOfMemoryException.
Add APIs for creating and manipulating Chart objects.
Add support for Hidden and Empty Cells options:
https://support.office.com/en-us/article/display-empty-cells-null-n-a-values-and-hidden-worksheet-data-in-a-chart-a1ee6f0c-192f-4248-abeb-9ca49cb92274
When a chart is inserted in a document, generated by SpreadProcessing or WordsProcessing, the chart seems to lack any bars. The reason is that some theme information is missing, which effectively makes shapes take their default color, which is transparent. The same applies for shapes inserted in any Document Processing-generated OOXML documents - docx, xlsx. Workaround: (applicable for Excel) Manually change the theme for the document in MS Excel: - Choose Page Layout -> Themes -> Themes dropdown -> Office.
ArgumentException with clarification similar to "'\u001f', hexadecimal value 0x1F, is an invalid character." is thrown when trying to export document containing characters which are not supported in XML document - such as some control characters like 0x00, 0x1F, 0x1B, etc. Such characters are described in the XML specification here: https://www.w3.org/TR/xml/#charsets. Although the escaped strings are not supported (see https://feedback.telerik.com/Project/184/Feedback/Details/190228 ), the library could prevent the exception and export the document successfully by skipping such characters. Workaround: remove such characters before the export. Check the following StackOverflow answer for some ideas on code for replacing the characters: http://stackoverflow.com/a/14323524/259206 Fix available in R3 2018 SP1 release.
Provide the ability to work with images in headers/footers of a worksheet. Note that large images put in headers are visualized as watermarks on printing/exporting to PDF.
Watermark in Excel: https://support.office.com/en-us/article/add-a-watermark-in-excel-a372182a-d733-484e-825c-18ddf3edf009
The row declaration is the following: <row r="8" spans="1:18" ht="15.75" x14ac:dyDescent="0.25"> The dyDescent attribute is described as follows: The dyDescent attribute is a double attribute, as specified in [XMLSCHEMA2/2] section 3.2.5, that specifies the vertical distance in pixels from the bottom of the cells in the current row to the typographical baseline of the cell content if, hypothetically, the zoom level for the sheet containing this row is 100 percent and the cell has bottom-alignment formatting. See section 2.2.4.12 for how this element integrates with the Office Open XML file formats specified in [ISO/IEC29500-1:2016]. The dyDescent attribute has a side effect; it sets the customHeight attribute to true even if the customHeight attribute is explicitly set to false. Note: Since the dyDescent attribute is not implemented, the height is not recognized to be custom and therefore it is not imported at all. The row has the default height.