custom-variable-reset-standardcustom-variable-reset-standard is a compiled Lisp function in `
cus-edit.el'. (custom-variable-reset-standard WIDGET) Restore standard setting for the variable edited by WIDGET. This operation eliminates any saved setting for the variable, restoring it to the state of a variable that has never been customized. The value that was current before this operation becomes the backup value, so you can get it again.