Currently, all libraries are loaded at set-up by the interpreter. All visible symbols, i.e. those listed in this appendix, are protected and cannot be redefined by the user.
It is easy to see when a symbol is protected: (a) it is colored blue by the Xplode editor, and (b) a false value is returned by the interpreter when asking for the evaluation of a redefinition of some protected symbol. The user may easily change this behavior, by either preventing the loading of some libraries, or by loading them as non-protected at set-up, or by loading some needed library on request during the work session. Let remember that the language is not case-sensitive.