Build 3.5.0.99 of xlsgen preserves 10+ workbook-level properties from XLSX files (and their variants).

Among the preserved properties are :
- date1904
- showObjects / hideObjectd
- showBorderUnselectedTables
- filterPrivacy
- promptedSolutions
- showInkAnnotation
- backupFile
- saveExternalLinkValues
- updateLinks
- hidePivotFieldList
- showPivotChartFilter
- allowRefreshQuery
- publishItems
- checkCompatibility
- autoCompressPictures
- refreshAllConnections
- defaultThemeVersion

A number of those properties affect the performance and size of files depending on their values (most are boolean values). For instance, the saveExternalLinkValues property is checked by default in Excel which means Excel saves a cache of all external references, which can be arbitrarily big. Unchecking this property in Excel's user interface ensures no such cache is saved in the file.