"blank line in fill mode, using .sp",
"tab in filled text",
"new sentence, new line",
- "invalid escape sequence",
+ "invalid escape sequence argument",
"undefined escape, printing literally",
"undefined string, using \"\"",
"skipping excess arguments",
"divide by zero",
+ /* related to escape sequences */
+ "incomplete escape sequence",
+ "invalid special character",
+ "unknown special character",
+ "invalid escape argument delimiter",
+
"unsupported feature",
"input too large",
"unsupported control character",