One-sentence point: the team aims for 99.9% successful requests across the most recent 30 days, with specific exclusions and internal consequences, but this is not a customer contract.
Plain-language explanation: “rolling 30-day window” means the measurement period moves forward each day. Planned maintenance is left out only when announced at least 72 hours ahead. The small permitted amount of failure is called the error budget. If that allowance is used up, ordinary releases stop; security fixes and incident-commander-approved changes may still proceed.
For support: describe this as an internal target, not guaranteed uptime or a basis for compensation. Glossary: service-level objective—internal reliability target; error budget—failure allowed within that target; release freeze—temporary stop on ordinary changes. Illustrative example: an announced maintenance window 48 hours ahead would not meet the stated 72-hour exclusion. Limits: the source does not define contractual uptime, compensation, or how successful requests are calculated. All numbers, exceptions, and the SLO/SLA distinction are preserved.