What do the different colors of text on the market data line mean?

Übersicht: 

The text colors (typically the numbers) in a market data line are used to indicate up and down movement of price and quantity.  The different colors and their meanings are:

 

Background: 

Yellow:  Indicates no change in size or price.

 

Green:  Indicates an upward movement in size or price.

 

Orange:  (or red) indicates a downward movement in size or price.

 

Purple:  For options, the price displayed in purple indicates the best price is not executing automatically at one or more of the exchanges displayed.

 

Magenta:  For inter-market spread orders, this color indicates the implied price of the order.

 

Light Blue:  Indicates that this was the last price at which the contract traded.