Create ZIP archives from XltX files in C#. Package one or multiple files, preserve names and related assets, and optionally protect the ZIP with AES....validate OOXML, or convert XLTX to XLT, XLSX, or another spreadsheet...XHTML XLM XLS XLSB XLSM XLSX XLT XLTM XLTX XML XOML XPS XSLFO...