You can use traditional TODO-comments in the strict format of the specification or the new twitter-styled comments of ntask. I highly recommend the latter, as it offers a lot more functionality.
Keywords should be in uppercase
For a task to be added, it has to validate. A valid task has a title of atleast ten characters and a keyword ofcourse.
Labels and assignee does not count as being part of the title
Tasks without an explicitly set assignee will retrieve the assignee "@none". Adding an assignee is done using the "@"-character as prefix of a string.
@unassigned is an alias to @none
Labels are prefixed with the "#"-character and can be filtered and searched. A label can contain a scalar value by surrounding it with brackets. Ex: pri[2]