• NotebookSave[notebook] saves the current version of a notebook in a file.
• NotebookSave[notebook, "file"] saves the notebook in the specified file.
• NotebookSave[notebook] saves the notebook in a file whose name is given by the notebook object notebook.
• NotebookSave writes out the Mathematica expression corresponding to the notebook, together with Mathematica comments which make it easier for the front end to read the notebook in again.
• New in Version 3.