How does proposition 2 1/2 affect the town's ability to levy additional taxes?

Proposition 2 1/2 provides for increases in the tax levy limit for Towns in different ways:

First, proposition 2 1/2 allows an automatic increase in the total levy of 2 1/2%. Raising the tax levy limit beyond 2 1/2% can also be done by a debt exclusion (a capital expenditure , e.g., to pay for a new high school), or through an override (e.g., an operational override to pay for fire, police, school, town administration, etc.). While a debt exclusion affects your taxes only until the debt is paid in full, an override is a permanent addition to the tax levy base over and above the proposition 2 1/2 limit.