Complex sentence: Some record achievements, (e.g. past politicians note the years of their terms of office) but nearly all (excepting those where this is impossible, including the Tomb of the Unknown Soldier) note name, year or date of birth and date of death.
Split into simpler sentences: Some record achievements (e.g., past politicians note the years of their terms of office). Nearly all (excepting those where this is impossible by definition, such as the Tomb of the Unknown Soldier) note name, year or date of birth, and date of death.