The organisation's shared definitions, for writing SQL about a business question: metrics (what revenue, MRR or churn mean, as SQL expressions), datasets (which table holds what, its fields and time fields), relationships (how tables join, by which columns) and notes your admins wrote about querying the data (naming conventions, fiscal calendar). Pass connectionId for the definitions that apply to that database (the organisation-wide ones plus its own); search filters by name, synonym or description. A metric's expression is the organisation's agreed wording for that number, so a query built from it agrees with the team's own reports.