fix: set <event> to 'Flood' per CAP 1.2 §3.2.4

[johnswarbrick]

Problem

The <info><event> field in published CAP alerts currently contains a reference to the message type, e.g Issue, Update or Remove rather than describing the hazard as required by the CAP 1.2 specification.

This PR fixes the issue by setting the <info><event> field for every alert to "Flood".

As a future piece of work, a more specific OET event term could be derived from the FWIS area code or warning type to be more specific, e.g. using Coastal Flood for coastal alerts instead of the generic Flood.

Examples from the live feed

Source: https://environment.data.gov.uk/cap/flood-alerts.atom

<msgType>Alert</msgType>
...
<info>
  <event>Issue</event>  <!-- Should describe the hazard, not the message type -->

<!-- Message 117004 (2026-03-07) -->
<msgType>Update</msgType>
...
<info>
  <event>Update</event>  <!-- Should describe the hazard, not the message type -->

<!-- Message 116867 (2026-03-06) -->
<msgType>Cancel</msgType>
...
<info>
  <event>Remove</event>  <!-- Should describe the hazard, not the message type -->

Every alert checked in the current feed exhibits this pattern — <event> always mirrors <msgType>.

CAP 1.2 specification

Per the OASIS CAP 1.2 standard, these are distinct fields with different purposes:

• <msgType> (§3.1) — the nature of the message: "Alert", "Update", "Cancel", "Ack", "Error"
• <event> (§3.2.4) — "The text denoting the type of the subject event of the alert message"

<msgType> describes what the message is doing (issuing, updating, cancelling). <event> describes the hazard (flooding).

The Google Public Alerts documentation further clarifies that <event> appears in alert titles and should be "short (less than 35 characters) and descriptive enough for the public to understand", with examples like <event>Tornado</event>.

Suggested <event> values

The OASIS CAP Event Terms List (ETL) v1.2 defines standardised event terms.

From that list, the following terms are relevant for the Environment Agency flood warning service:

OET Code	Event Term
OET-081	Flood
OET-042	Coastal Flood
OET-079	Flash Flood
OET-140	Overland Flood

Using Flood for all alerts is a pragmatic starting point and is implemented in this PR.

As a future piece of work, the event term could be derived from the FWIS area code or warning type to be more specific, e.g. using Coastal Flood for coastal alerts instead of the generic Flood.

Impact

• CAP consumers (including aggregators, alerting platforms, and Google Public Alerts) rely on <event> to categorise and display alerts by hazard type
• With the current output, all Environment Agency flood alerts appear as event type "Update" or "Alert", making them indistinguishable from other hazard categories
• The <event> value is what end users see first — "Update" tells them nothing; "Flood" tells them everything they need

Root cause

The <event> value comes from the upstream FWIS system and passes through processMessage.js unchanged. The test fixtures in this repository confirm the upstream has historically sent incorrect values in this field (e.g. "064 Issue Flood Alert EA" in test/lib/functions/data/capAlert.json).

The updateReferences() function already transforms <msgType> and <references> but does not touch <event>. A similar one-line transformation resolves the issue.

Fix

This PR sets <event> to Flood after the existing updateReferences() call in lib/functions/processMessage.js:

// Set <event> to describe the hazard type per CAP 1.2 §3.2.4.
// The upstream FWIS system incorrectly sends msgType values ("Alert",
// "Update", "Cancel") or internal action codes in this field.
xmlResult.alert.info[0].event[0] = 'Flood'

As mentioned above, as a future piece of work, the event term could be derived from the FWIS area code or warning type to be more specific, e.g. using Coastal Flood for coastal alerts instead of the generic Flood.

References

• CAP 1.2 spec §3.2.4
• OASIS CAP ETL v1.2
• Google Public Alerts
• Live feed