JSON string of the DSL when filters use operators like $gt/$in/$contains/$and/$or. Date fields and the system timestamps created_at/updated_at also accept $datePreset ("today", "yesterday", "this_week", "last_week", "this_month", "last_month", "this_quarter", "last_quarter", "this_year", "last_year"), and $inLast/$inNext rolling windows (a day count like 7, or {"amount":2,"unit":"weeks"} with unit days|weeks|months|quarters|years). On a date field, $gt/$gte/$lt/$lte take a day ("2026-11-03"), an ISO date-time with its offset or epoch ms; a top-level "timeZone" (IANA) says which zone a day bound means. A filter naming a field the object does not have is an error. Example: {"filter":{"updated_at":{"$datePreset":"this_month"}}}.