Save (AS Language)

Inside Macintosh: AppleScript Language Guide / Part 3 - Appendixes

Appendix B - Scriptable Text Editor Dictionary / Scriptable Text Editor Commands

Save
The standard Save command is defined on page 112. The Scriptable Text Editor version behaves like the standard version, except that it has an extra optional parameter (as text) that allows you to save Scriptable Text Editor files as text files (files of type "TEXT"). Without this parameter, files are saved as Scriptable Text Editor files.
save referenceToObject [in referenceToFile ] [as text]
In addition, the direct parameter of the Scriptable Text Editor version cannot be a list; it must be a reference to a single object. For example, the following statement results in an error:
tell application "Scriptable Text Editor"
   save documents 1 thru 3
end tell
--result: error; Save can handle single objects only