Related Clues:

• Twelve-mo. spans
• '04, '08 and others
• Times for revolutions: Abbr.
• Hundreds of wks.
• Calendar ref
• Letter signoff, for short
• Vintage nos.
• 1000 and 2000 e.g.
• Eon units: Abbr.
• Sch. terms
• Era divs.
• '01 and '06, e.g.
• Decade divisions: abbr.
• Decade parts (Abbr.)
• Tree-ring meas.