MicroGrams format and operating notes.

Basic payload format

A raw MicroGrams payload begins with the form ID, followed by encoded responses, optional prompt fields, optional comment text, and optional datecode.

F!101 232335222 Bad Propagation #FJDE

Optional station or group addressing belongs outside the raw payload.

@ARCWC F!101 232335222 Bad Propagation #FJDE

Cross-mode declaration

When carrying a MicroGrams payload from JS8Call or VarAC to another mode, append the public site URL after the datecode and optional authentication code. The URL is outside the raw form payload and helps an unfamiliar recipient reach the decoder.

F!101 232335222 Bad Propagation #FJDE https://micrograms.org
F!101 232335222 Bad Propagation #FJDE 20S https://micrograms.org

The full https:// form is intentional because many receiving applications recognize it as a clickable link. The decoder accepts the complete line and ignores the URL while interpreting the payload.

Prompt fields

Prompt fields use two-character IDs such as [ST], [GR], [CT], and [ET]. Keep them short.

Recommended location use: state, tactical area, or Maidenhead grid. Put town, address, landmark, or detail in the comment only when needed.

Form ID numbering convention

Use these ranges when creating or publishing additional forms so operators avoid collisions. Same Form ID should mean the same form definition. If you change the questions, answers, prompt fields, or meaning of a form, use a different unused Form ID.

• 000-099: preliminary or proposed forms
• 100-199: informational, informal, non-emergency
• 200-299: reserved for future allocation
• 300-399: emergency, exercise, and situation reports
• 400-499: reserved for future allocation
• 500-599: surveys of general conditions
• 600-699: reserved for future allocation
• 700-799: group and net forms
• 800-899: reserved for future allocation
• 900-999: miscellaneous, overflow, local, or experimental use

Optional authentication code

Some operators may append a three-character authentication code after the datecode.

F!101 232335222 Bad Propagation #FJDE 20S

MicroGrams carries and labels this code but does not generate or validate it. Validation requires the outside authentication method and shared key agreed to by the operators.

Datecode

The datecode begins with # and uses four compact characters for month, day, hour, and two-minute-resolution minute.

#FJDE

MicroGrams generates datecodes using UTC. The datecode does not include a year.

Typical character targets

• APRS message: about 67 characters
• SMS GSM: 160 characters
• SMS Unicode: 70 characters
• Meshtastic conservative target: about 200 characters
• General low-bandwidth target: about 240 characters

Treat these as practical planning targets, not universal guarantees.

Sending through APRS

Select APRS message in the Tool, then send the complete generated cross-mode line as the APRS message text in one packet. Keep the line at or below the displayed 67-character target and do not transmit a truncated payload.

Beacon comments and position reports have less space because their location and other fields consume characters. For those packets, sending the MicroGrams payload as a separate APRS message is recommended.

Offline and shared local forms

The standalone offline tool is intended for disconnected or RF-only operations. It carries the current repository forms in one self-contained file and can also open shared MicroGrams .txt form definitions from the local computer. No form or message is uploaded, and the transmitting and receiving stations do not need to reach the MicroGrams website.

A custom form does not need to be published on the server or permanently embedded in the offline tool. Each station can open the same form file locally and use it for both encoding and decoding.

1. Download the offline tool and any required local forms before connectivity is lost.
2. Share the exact same .txt form definition with every participating station.
3. Select Open local form(s) and choose the saved form file.
4. Verify that the Form ID and definition hash match at every station before exchanging payloads.

Repository forms remain embedded in the offline tool. Local forms are available for the current offline session, so retain their original files for later use.

Inspiration and project lineage

MicroGrams builds on compact form workflows first developed and widely used within the JS8Spotter and JS8Call community through the work of Joe Lyman, KF7MIX. The original compact forms guide remains a useful reference for how shared form definitions, coded responses, and prompt fields were established in those systems.

The primary JS8Spotter form repository is maintained by SITREPNET. Its @SITREP JS8Spotter settings guide documents the shared settings and files used for interoperable JS8Spotter operation.

MicroGrams is an independent, lightweight implementation intended to make the same basic compact-messaging idea available through an ordinary web browser, across many text-based communications paths, and in a downloadable offline tool. It may mirror selected forms and host community-developed forms, but it is not the official JS8Spotter repository.