An SLA is a way to empirically measure contractual performance and Co-Party(ies) commitments. Typical types include Spend, Cost, Quality, Delivery, Innovation, Risk, Solutions, Realization of Benefits, Compliance, Cultural Alignment, and Maintenance & Support Services.  Measurements are captured via surveys taken by selected participants and then tracked and charted against a set target.  You can additionally track financial, numeric and/or emotional and other impacts.  As a best practice, we recommend capturing the data and/or documents that determine SLA performance and reference it in these sections so that you can easily refer to it for extreme clarity.