2. format. Xls: Excel version 97-2003, which can have macros.
3. format. Csv: Comma-separated text file, which is easy to be compatible with other programs. Save only active sheet.
4. format. Pdf: a portable document format, and the data in the file is not easy to modify.
Extended data:
File extension is a necessary part of a file.
The file may or may not have an extension. Open a file. Files without extension need to be opened by a program, and files with extension will be automatically opened by a set program (if any). File extensions are part of regular files, but files do not necessarily need extensions.
Second, the file extension indicates the type of file.
The file extension can be set artificially. Files with TXT extension may be pictures. Similarly, files with MP3 extension may also be videos. ?
Baidu Encyclopedia-Common File Extensions