+encoding. This attribute is meaningful only when `:coding-type' is
+`ccl'.
+
+`:inhibit-null-byte-detection'
+
+VALUE non-nil means Emacs ignore null bytes on code detection.
+See the variable `inhibit-null-byte-detection'. This attribute
+is meaningful only when `:coding-type' is `undecided'.
+
+`:inhibit-iso-escape-detection'
+
+VALUE non-nil means Emacs ignores ISO-2022 escape sequences on
+code detection. See the variable `inhibit-iso-escape-detection'.
+This attribute is meaningful only when `:coding-type' is
+`undecided'.
+
+`:prefer-utf-8'
+
+VALUE non-nil means Emacs prefers UTF-8 on code detection for
+non-ASCII files. This attribute is meaningful only when
+`:coding-type' is `undecided'."