( ▲ ) A black triangle in front of a
link indicates pop-up information directly related to the discussion. Just mouse-over the blue link that follows the symbol.
A green square ( 
) in front of a link indicates information that's important to
what's being discussed. We cover this information in the interactive tests
and puzzles.
A yellow square ( 
) indicates helpful background reading.
This material is not included on the interactive tests,
but instructors may include the readings on their own tests.
A blue square ( 
) indicates technical information designed
for advanced classes and professionals.
A red square ( 
) indicates external links with related
information not included on the interactive tests -- but your instructor, of
course, has the option of asking that you read this information.
