This function has several safety measures built in and saves the current scene to a Maxfile of specified version and attaches a "_M201x" suffix to the filename automatically. Macroscripts are also created (on demand only) to make it easy to map the function call to keyboard/menu or button.
The full signature of the saveToprevious function looks like this:
SaveVersionHandler.SaveToVersion <MaxVersion> [fileName:<filename>] [quiet:true|false]
eg. this saves to Max 2010 version, the filename will be "<currentscenename>_M2010.max".
If this scene already exists, you will be prompted to overwrite or cancel...
The script itself is future proof, and adapts to future Max versions automatically
By default there are no macroscripts for UI access installed.
You can create them easily by calling the following function ( required only ONCE).
This creates macroscripts for all versions the actual 3ds Max version is able to save to.
Those macroscripts can immediately be assigned to keyboard/menu or button after that
Find more info and download here: