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 sending outside JS8Spotter/JS8Call, add a short declaration so the recipient knows the text is a MicroGrams payload.

MICROGRAMS F!101 232335222 Bad Propagation #FJDE
MCF F!101 232335222 Bad Propagation #FJDE

MICROGRAMS is clearest for new users. MCF is shorter for tighter paths.

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

Obsolete forms: F!501 and F!502 are obsolete and replaced by F!504. Obsolete forms are not included in this mirror or in current JS8Spotter update files.

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.

Original implementation reference

One of the earliest and most widely used compact form implementations was developed for the JS8Spotter ecosystem by Joe Lyman, KF7MIX.

The primary JS8Spotter form repository is maintained by SITREPNET.