{
  "event": "generate_lead",
  "event_parameters": [
    {
      "name": "old_name",
      "note": "The name before the rename: lead_form, 9 characters.",
      "required": true,
      "type": "string"
    },
    {
      "name": "new_name",
      "note": "The name after the rename: generate_lead, 13 characters. A recommended name, so it also gains the lead reports.",
      "required": true,
      "type": "string"
    },
    {
      "name": "name_limit",
      "note": "Event names are at most 40 characters.",
      "required": true,
      "type": "string"
    }
  ],
  "rules": [
    "GA4 has no rename button for an event. There is no way to rename an event's history.",
    "The supported way to change a name is to modify a created event, or to create a new event from the existing one.",
    "A modification or a new event applies only to data collected after the change; history is never renamed or rewritten.",
    "After a rename, the report shows two rows for a while: the old name, which stops growing, and the new name, which starts at zero.",
    "Event names are case-sensitive and at most 40 characters; they start with a letter and use letters, numbers, and underscores.",
    "Plan names first: the rename is cheap, the split history is permanent."
  ],
  "source": "Analytics Help \u2014 Create or modify key events (support.google.com/analytics/answer/12844695) and [GA4] Collection and configuration limits (support.google.com/analytics/answer/9267744), opened 11 November 2026",
  "verified_example": {
    "arithmetic_check": {
      "checked_with": "Python 3.12.3, run 11 November 2026",
      "computation": "13 - 9",
      "matches_limit_field": true,
      "result": 4
    },
    "event": "generate_lead",
    "history": {
      "events_under_new_name": 0,
      "events_under_old_name": 412,
      "note": "The 412 events collected under lead_form stay under lead_form; they are never renamed."
    },
    "names": {
      "length_change": 4,
      "name_limit": 40,
      "new_name": "generate_lead",
      "new_name_length": 13,
      "new_name_within_limit": true,
      "old_name": "lead_form",
      "old_name_length": 9,
      "old_name_within_limit": true
    },
    "source": "Lengths counted from the names; the no-rename rule and the 40-character limit are Google's"
  }
}