ECIG Recommendations for a CAP EAS Implementation Guide

EAS CAP Industry Group (ECIG) — EAS-CAP Implementation Guide Subcommittee Version 1.0 — 17 May, 2010

Original PDF: ECIG-CAP-to-EAS_Implementation_Guide-V1-0.pdf © 2010 EAS-CAP Industry Group. All Rights Reserved.

Table of Contents

1. Introduction
2. General Requirements and Specifications
3. Implementation Guide Requirements and Specifications
4. Notes for Originators and Origination Software
5. CAP/EAS Examples
6. CAP-to-EAS Validation Criteria

1. Introduction

1.1 Purpose

Public warnings intended for transmission over the Emergency Alert System (EAS) can be encoded in Common Alerting Protocol (CAP) messages in various ways. The EAS-CAP Industry Group (ECIG) produced this Implementation Guide to reduce areas of uncertainty in how an alert will be presented to the public via CAP/EAS, so that originators and distributors of alerts can deliver the intended message to the public, regardless of the vendors or platforms involved.

Core goal: All CAP-to-EAS devices MUST generate the EXACT same EAS message for a given CAP message.

1.4 Terminology

Key words (per RFC 2119): MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, SHOULD NOT, RECOMMENDED, MAY, OPTIONAL.

1.5 References

• [3] FCC EAS Rules: 47 CFR Part 11
• [4] CAP v1.2 specification (OASIS)
• [5] CAP v1.2 USA IPAWS Profile v1.0 (OASIS)

2. General Requirements and Specifications

2.1.1 Specific mimeTypes

ECIG recommends these mimeTypes for audio resources:

audio/x-ipaws-audio-mp3
audio/x-ipaws-audio-wav
audio/x-ipaws-streaming-audio-mp3

2.1.2 EASText Parameter

ECIG recommends a new EASText CAP <parameter> element allowing originators to dictate the exact text for video crawl and TTS. If absent, text is derived from other CAP fields (see §3.6).

3. Implementation Guide Requirements and Specifications

3.2 EAS Alert Activations

An EAS activation comprises up to four elements:

1. Header code — Sent three times, with a one-second pause after each transmission.
2. Attention signal — Two-tone signal, used if and only if a message follows.
3. Message — Audio message following the attention signal.
4. End of message (EOM) — Sent three times, with at least a one-second pause after each.

3.3.1 Multiple Parameters

When multiple <parameter> elements have the same valueName, and the valueName is not meant to describe a list, recipients SHALL accept only the first occurrence.

3.4 Constructing the EAS Header Code from CAP IPAWS v1.0

3.4.1.1 ORG (Originator)

The EAS Originator Code SHALL come from the CAP <info><parameter> block with <valueName> of "EAS-ORG".

Valid originator codes (FCC Part 11.31(d)):

Note: EAN originator was removed in a 2002 update; do not use.

3.4.1.2 EEE (Event Code)

The EAS Event Code SHALL be represented using <info><eventCode> with <valueName> of "SAME". The value is case sensitive (uppercase). A CAP message without a SAME event code SHALL NOT be aired.

3.4.1.3 PSSCCC (Location Codes)

Each EAS location code SHALL come from <area><geocode> with <valueName> of "SAME". Rules:

• At least one <geocode> must be present.
• Only the first 31 geocodes are placed in the ZCZC string, in the order encountered (required for duplicate detection).
• 000000 indicates the entire United States and Territories.

3.4.1.4 TTTT (Duration)

The EAS duration SHALL be calculated as <info><expires> minus <alert><sent>.

TTTT is encoded in HHMM format (e.g., 0100 = 1 hour, 0130 = 1 hour 30 min).

Rounding rules:

• Round UP to the next permitted interval.
• If duration ≤ 0 → alert is expired, SHALL be ignored.
• FCC Part 11.31(c) caps most alerts at 0600 (6 hours).

3.4.1.5 JJJHHMM (Issue Time)

Derived from <alert><sent> in ISO 8601 format. Julian day-of-year + UTC hour + UTC minute.

3.4.1.6 LLLLLLLL (Station ID)

Always inserted by the EAS device; not specified by any CAP element. SHOULD be the call sign of the CAP-to-EAS device (up to 8 characters).

3.4.1.7 Governor's Must-Carry

Messages where Governor's must-carry authority applies SHALL include:

<parameter>
  <valueName>EAS-Must-Carry</valueName>
  <value>True</value>
</parameter>

This overrides originator and event code filtering for automatic forwarding. Location filters and duplicate prevention still apply.

3.5 CAP EAS Audio Processing

3.5.1 Audio Selection Priority

1. If <resource> with <resourceDesc> = "EAS Broadcast Content" is present → SHALL use that audio.
2. If no attached audio and device supports TTS → SHALL render TTS per §3.5.4.
3. If no TTS capability → send EAS-codes-only with no audio.
4. If a URI cannot be accessed within a reasonable time (≤2 minutes for download, ≤30 seconds for streaming) → fall back to TTS.

3.5.2 Recorded Audio Specs

• MP3: mono, 64 kbit/s, preferably 22.05 kHz (or 44.1 kHz)
• WAV: mono, 16-bit PCM, 22.05 kHz
• <resourceDesc> value SHALL be "EAS Broadcast Content"
• FCC Part 11 two-minute limit on EAS audio MUST be enforced for all alerts except EAN.
• Text deletions indicated by *** (three asterisks) SHALL be followed by a one-second pause.

3.5.3 Streaming Audio Specs

• <resourceDesc> SHALL be "EAS Broadcast Content".
• Streaming methods: MP3 HTTP progressive-download or HTTP streaming MP3 server.

3.5.4 Text-to-Speech

• TTS audio SHALL be an exact translation of the Alert Text (see §3.6).
• Text deletions indicated by *** SHALL be followed by a one-second pause.
• FCC Part 11 two-minute (120-second) limit applies, except for EAN.

3.6 Constructing Alert Text (TTS / Video Crawl)

Maximum text length: 1800 characters.

3.6.1 Whitespace Rule

Before adding any string to TTS or display output, the device SHALL:

1. Remove leading and trailing whitespace.
2. Replace all whitespace characters (space, form-feed, newline, carriage return, tab) with a single space.

3.6.2 EASText Parameter

If <parameter><valueName>EASText</valueName> is present, the EAS receiver SHALL use its <value> verbatim as the alert text (for video crawl and TTS).

3.6.3 FCC Required Text

The FCC requires alert text to include at minimum:

A sentence containing the Originator, Event, Location, and valid time period constructed from the EAS ZCZC Header Code (FCC Part 11.51(d)).

Example:

A CIVIL AUTHORITY HAS ISSUED A HAZARDOUS MATERIALS WARNING FOR THE
FOLLOWING COUNTIES/AREAS: District of Columbia, DC; AT 5:34 PM ON
MAR 11, 2009 EFFECTIVE UNTIL 6:34 PM.

3.6.4 Alert Text Construction

The complete alert text is assembled in this order:

[FCC Required Text]
[If EASText present: EASText value]
[Otherwise:]
  [Optional: "Message from " + <senderName>]
  [<description> content (partial if needed)]
  [<instruction> content (partial if needed)]

Space allocation algorithm when description + instruction exceed remaining space:

half = (1800 - len(fcc_required_text + sender)) / 2
if len(description) < half:
    max_description = len(description)
    max_instruction = half + (half - max_description)
else:
    max_description = half
    if len(instruction) < half:
        max_instruction = len(instruction)
        max_description = half + (half - max_instruction)
    else:
        max_instruction = half

Text truncations SHALL be indicated by ***.

ECIG does NOT recommend using <headline> or <areaDesc> in the alert text display.

3.7 Languages

• A CAP-to-EAS device SHALL provide for a primary language specification.
• Multiple <info> blocks may be used for multiple languages.
• Each <info> block SHOULD contain a <language> element; default is en-US.
• If multiple <info> blocks in the same language exist, only the first is processed.
• TTS audio per language is limited to 120 seconds. EOM is sent after the primary language, then additional languages follow.

3.8 CAP msgType Handling

3.9 Test Messages

• CAP <status> of Test, Exercise, or Draft MUST NOT be placed on air.
• EAS test messages (RMT, RWT, NPT, DMO, NMN) MUST have <status> of Actual to go on air.

Recommended fields for EAS on-air tests:

<status>Actual</status>
<urgency>Unknown</urgency>
<severity>Minor</severity>
<certainty>Unknown</certainty>

3.10 Older CAP Protocol Versions

• When processing CAP 1.1 messages without an originator, SHOULD assume CIV.
• A <geocode> with <valueName> of FIPS6 SHOULD be accepted and handled as SAME.

3.11 Duplicate Alert Handling

CAP duplicate: Same <identifier>, <sender>, and <sent>.

EAS duplicate: Byte-wise comparison of ZCZC strings, excluding the LLLLLLLL (Station ID) field.

Rules:

• Duplicate CAP messages: render only one to EAS.
• Once an EAS message is aired, duplicate EAS alerts SHALL NOT be automatically aired.
• If both CAP and EAS versions of an alert exist (neither aired), SHOULD prefer the CAP version.

4. Notes for Originators and Origination Software

1. EAS-ORG parameter MUST be provided.
2. A SAME event code MUST be provided (<eventCode><valueName>SAME</valueName>).
3. At least one <geocode> with <valueName> of SAME MUST be provided. Only first 31 are used.
4. EAS devices may round expiration times up to the nearest valid EAS duration.
5. EASText parameter MAY be provided for video crawl / TTS control.
6. <areaDesc> is ignored by EAS devices; location details should go in <description>.
7. Total alert text MUST be ≤ 1800 characters; TTS truncated at 120 seconds.
8. Audio MAY be provided in WAV or MP3 format; use MP3 over WAV.
9. EAS messages aired only if <scope> is Public.
10. EAS messages aired only if <status> is Actual.
11. <msgType> values processed for air: Alert, Update, Cancel.

5. CAP/EAS Examples

5.1 Hazardous Materials Warning — Example ZCZC String

ZCZC-CIV-HMW-011001+0100-0702334-LLLLLLLL-

Generated alert text:

A CIVIL AUTHORITY HAS ISSUED A HAZARDOUS MATERIALS WARNING FOR THE FOLLOWING
COUNTIES/AREAS: District of Columbia, DC; AT 5:34 PM ON MAR 11, 2009 EFFECTIVE
UNTIL 6:34 PM. Message from CAP alert central. [description] [instruction]

5.2 Required Monthly Test

ZCZC-CIV-RMT-053029-053031-053035-053033-053061+0100-0252000-LLLLLLLL-

• <status>Actual</status> — required for on-air broadcast
• <urgency>Unknown</urgency>, <severity>Minor</severity>, <certainty>Unknown</certainty>

5.3 National Emergency Action Notification (EAN)

ZCZC-PEP-EAN-000000+9930-0742256-LLLLLLLL-

• Originator: PEP; Location: 000000 (entire United States)
• Audio: live streaming MP3 resource

5.4 National Emergency Action Termination (EAT)

ZCZC-PEP-EAT-000000+0030-0752200-LLLLLLLL-

5.5 CAP System Test (status=Test — NOT aired)

<status>Test</status>  <!-- MUST NOT be broadcast -->

6. CAP-to-EAS Validation Criteria

6.5 Validation Order

1. CAP conformance — Legal XML format. Failure → Rejected.
2. CAP/EAS validation:
   • Missing required CAP+EAS elements → Rejected
   • Invalid EAS-compatible elements → Rejected
   • Missing optional EAS elements → Ignored (with defaults where defined)
3. Acceptance → further filtered by EAS rendering rules (event codes, FIPS, etc.)

6.6 Result States

6.7 Required Elements for EAS Translation

Alert block (all required): <alert>, <identifier>, <sender>, <sent>, <status>, <msgType>, <scope>

Info block: <info>, <eventCode> (with valueName=SAME)

Area block: <area>, <geocode> (with valueName=SAME, at least one)

Conditional (if <resource> present): <resourceDesc>, <mimeType>, <uri>

Additional IPAWS conformance requirements: <alert><code> containing "IPAWSv1.0", <info><expires>, <parameter><valueName>EAS-ORG

Validation Table — Key Mappings