Release_Notes.md

2026-05-05 - V4

• ⛓️‍💥 Breaking Change(s)
  • Removal of GetSheetFileName(int offsetSheetId);
  • Removal of GetDefinedRange via int sheetId
  • Removal of Index property from ISheet
  • Internal Creation of WorkBooks
  • Internal implementation of IOpenXmlWorkBookReader::GetSheetNames now returns the relative path to the sheetName
  • CellValue is now a class, therefore no need to use .Value
  • ICell.CellValue is now nullable
• ArrayPool support has been added to ThreadStringBuilderPool using ArrayPool.
• Release-specific optimizations added
  • EnableTrimAnalyzer: true
  • TieredCompilation: true
  • TieredCompilationQuickJit: true
  • TieredCompilationQuickJitForLoops: true
• Implement System.DBNull return option, for empty cells
  • Implement INullRow return option, for empty rows
  • Update tests to use INullRow detection
• Implement GetCell###(string columnLetters, ...) #8
• Implement System.DBNull return option, for empty cells
• Mark up usage of userdefined cells styles for V5
• Remove in usages (Supposed to not benefit !)
• Make use of ThreadStatic in XlsbRow
• Remove secoundary usage of a struct
• Re-introduce the CellConversion for the XLSX cell types
• Use ValueTask and reduce memory allocations in some hot paths
• Cell object type 📅
  • "Best Effort" Operator based conversion
  • TryGetType will return out type, if stored as that type.
• Add Ecma376StandardProvider
• Add StylesExtractor
• Attempt to make use of the Cell types
• Tinker with some MethodImpl
• Add _iStyleRef and start to add formatting based on it
• Fix fallout from making CellValue is now a class
• 🚀 2026-05-05