According to the Linux+ Guide to Linux Certification 2nd ed., most configuration files on Linux systems are delimited using the colon symbol (:) while the awk command uses spaces or tabs as delimiters for each field in a line.
SudoKing, please note that the hash symbol (#) allows the commenting of lines, not the delimiting of lines. This is not to be confused with a hashpling (such as #!/bin/bash) which is located on the first line in a shell script, and specifies the pathname to the shell that interprets the contents of the shell script.