You are also encouraged to include hashtags in your log messages, regardless of what API you use. A hashtag is composed of a hash (#) symbol, followed by at least four non-whitespace characters, terminated by whitespace or the end of the message. Hashtags may not begin with a number. Additionally, any custom ASL key that begins with a hash is treated as a hashtag. The Console application and the logging APIs understand hashtags on OS X v10.6 and later.