Priority codes rank signals into three tiers: an alarm that interrupts everything, a notice that needs attention soon, and routine traffic that can wait, and only the alarm tier may use the loud channels that wake the settlement. When two signals arrive at once the higher tier wins, and every alarm must be followed by a clear or a cancel, because false alarms met with blame train sentries to wait for certainty and the wait is the lost time.
Part of Signal Systems and Communication
Priority and urgency codes decide which signals interrupt, which wait, and which channels each tier may use.
Three Tiers Are Enough
Telegraph practice uses four precedence levels: EMERGENCY, PRIORITY, WELFARE and ROUTINE, with EMERGENCY allowed to interrupt other traffic (Protocols). A settlement using flags, horns and runners needs fewer.
| Tier | Meaning | Channel | Receiver’s duty |
|---|---|---|---|
| Alarm | Danger now; execute the plan | Horn, drum, bell, fire | Stop what you are doing |
| Notice | Attention soon: visitors, a patrol overdue | Lamp, flag, whistle between posts | Acknowledge, act within minutes |
| Routine | Information that can wait | Runner, written note | Read at next convenience |
The alarm tier uses the pattern the parent article says should be the simplest action. Everything else is below it.
Rules That Keep The Tiers Honest
- Only alarms use the alarm channel. If the settlement horn sounds for a lost goat, the next horn is ignored.
- Higher tier preempts lower. A post that is sending a notice stops when an alarm sounds; a runner with a routine message waits.
- Same tier: first come, first served. The receiver acknowledges the first and asks the second to repeat.
- Every alarm ends with a clear or a cancel. Without one, people stay at stations indefinitely and trust erodes.
- A maximum alarm duration. After a set time with no new information, the post commander asks for a status by runner.
Worked Example: What A False Alarm Costs
The figures are example inputs to show the method, not measurements.
- 40 people leave work for an assembly that lasts 2 hours: 40 x 2 = 80 person-hours lost.
- One false rally a month for a year: 12 x 80 = 960 person-hours, which is 24 hours each for each of the 40 people.
- The first cost is visible; the second is not. A sentry who is publicly blamed for a false rally will, next time, wait to be sure, and a threat does not wait.
A quick, plain cancel (“false alarm, a loose animal”) and an after-action note cost the sentry nothing and keep the habit of sounding early. The corpus makes the same point for a guard dog: reward each correct alert and never punish a false one (Alert Training).
Method: Setting Up The Tiers
Step 1: List the messages by tier and mark which are alarms.
Step 2: Give each tier its channels. An alarm may use any channel; a notice never uses the settlement horn.
Step 3: Add clear and cancel patterns to the code table. See Simple Code Tables.
Step 4: Write the false-alarm rule down. The sentry who sounds an honest false alarm is thanked, and the circumstances are reviewed without blame.
Step 5: Review every month. Count alarms, notices and false alarms; if routine traffic is creeping onto the alarm channel, restate the rule.
Common Mistakes
- Every message marked urgent. Then none is.
- No cancel signal. A mistaken alarm stays live.
- Blame for false alarms. It buys silence, not accuracy.
- A tier system nobody has drilled. In the dark nobody remembers which tier a message was.
What’s Next
- Learn next: Authentication and Security — making sure an alarm really came from your own post
- Combine with: Relay Networks — passing tiered messages along a chain