Each field of keywords.txt is separated by a single true tab. Leading spaces on a keyword identifier causes it to not be recognized by the Arduino IDE. On Arduino IDE 1.6.5 and newer an unrecognized keyword identifier causes the default editor.function.style highlighting to be used (as with KEYWORD2, KEYWORD3).
Each field of keywords.txt is separated by a single true tab. Leading spaces on a keyword identifier causes it to not be recognized by the Arduino IDE. On Arduino IDE 1.6.5 and newer an unrecognized keyword identifier causes the default editor.function.style highlighting to be used (as with KEYWORD2, KEYWORD3).
Reference: https://github.com/arduino/Arduino/wiki/Arduino-IDE-1.5:-Library-specification#keywords