Variable: indent-tabs-mode
indent-tabs-mode is a customizable and buffer-local variable defined
in indent.c.
Documentation
Indentation can insert tabs if this is non-nil.
Probably introduced at or before Emacs version 18.
Key Bindings
Source Code
// Defined in /usr/src/emacs/src/indent.c
DEFVAR_BOOL ("indent-tabs-mode", indent_tabs_mode,
doc: /* Indentation can insert tabs if this is non-nil. */);