Related Clues:

• Uno, ___, tres
• Tres minus uno
• First of a pair of lists
• Mohawk and others
• Base of el sistema binario
• Companion of don'ts
• __ Equis: Mexican beer
• Presqu' ____
• PC operating system
• Early Windows underpinning
• Buns, e.g.
• List of suggested actions
• Bob and flip
• Operating system of a computer, in short
• Politeness