The top row of each line contains the line's attributes. You can customize what attributes are displayed here using the Show/Hide button. See Customize Line Information for details.
Blue squares surround the dates that a pairing operates on a line.
The blue square around the 3 indicates that this is a one day pairing starting on the 3rd of the month.
The blue square around the 4 and 5 indicates that this a two day pairing starting on the 4th.
Hover your mouse over any date that has activity to view information on the pairing or reserve day.