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Emergency Alert System information
Common Alerting Protocol (CAP)Integrated Public Alert and Warning System (IPAWS)
Wireless Emergency Alerts (WEA)
Operational tips and background for Alert Originators:
- Area Maps for EAS Operational areas
- Tips for Alert Originators using IPAWS, EAS and WEA
- Historical IPAWS dataset analysis
- 2021 National Periodic Test - PBS WARN map
- Wireless Emergency Alert (WEA) GSM-7 Character set
Technical suggestions for EAS Participants:
Technical suggestions for Alert Origination Software vendors:
- IPAWS Broadcaster EAS-Device Alert Retrieval Interface Suggestion (PDF) [2 pages]
- Improving Wireless Emergency Alerts Rules and Specifications (PDF) [29 pages]
- Unicode Constraints
Creating CAP Alerts (PDF) [2 pages]
Unicode and UTF-8 encoding issues are common. The Unicode consortium has done a lot of work in later Unicode versions. I tried to distill guidance based on what I saw in CAP messages into a couple of pages, but Alert Origination Software vendors should also look at the Unicode documents. - XML Constraints
Creating CAP Alerts (PDF) [7 pages]
CAP XML data type issues is a bit more challenging because the original Oasis Common Alerting Protocol (CAP) specifications were intentionally vague. Vague standards are good for committee consensus, but bad for implementation and interoperability. Different Alert Origination Software vendors intepreted the Oasis CAP standards different ways. And each vendor will likely assert their intepretation was correct. - Hints Consuming XML CAP
Alerts (PDF) [2 pages]
Some good housekeeping guidance for software which consumes CAP messages. Unicode processing is a common issue. It also explains the reason for the CAP data type guidance above. The issues aren't as noticable with English language CAP messages. Windows-1252 characters such as smart quotes cause most of the issues. But issues showed up with some Spanish language CAP messages, and were extremely problematic with a CAP message using non-latin characters. - Guidance for IPAWS Common
Alerting Protocol (CAP) Elements and Sub-element Data (PDF) [33
pages]
This guidance attempts to follow the Common Alerting Protocol philosophy -- one CAP message is intended to be distributed by multiple alerting channels. The guidance is intended to improve the consistency of CAP messages across all IPAWS distribution channels. Some items improve interoperability with different implementations, such as specifying case-sensitive versus case-insensitive values. Other items would improve the public presentation of alerts, but don't affect the operation of the alert system.