on output. */
#define CODING_FLAG_ISO_DESIGNATE_AT_BOL 0x0400
+/* If set, do not encode unexpected charactes on output. */
+#define CODING_FLAG_ISO_SAFE 0x0800
+
+/* A character to be produced on output if encoding of the original
+ character is prohibited by CODING_FLAG_ISO_SAFE. */
+#define CODING_INHIBIT_CHARACTER_SUBSTITUTION 077 /* `?' */
+
/* Structure of the field `spec.iso2022' in the structure `coding_system'. */
struct iso2022_spec
{
function `set-terminal-coding-system'. */
extern struct coding_system terminal_coding;
+/* Coding system to be used to encode text for terminal display when
+ terminal coding system is nil. */
+extern struct coding_system safe_terminal_coding;
+
/* Coding-system of what is sent from terminal keyboard. This
structure contains information of a coding-system specified by the
function `set-keyboard-coding-system'. */