Nonemm/docs/n1mm-interop.md

# Opening a Nonemm log in N1MM

Checked on 2026-08-27 against N1MM Logger+ 1.0.11031 by writing a log here,
copying it to a Windows machine and opening it there. N1MM read the contest, its
categories and the contacts.

Three things had to be right, and none of them is obvious from the schema.

## The `Contest` table needs a row for the contest

`ContestInstance` says which contest a log is; the `Contest` table says what that
contest *is*. N1MM reads it in `Contest.FromRow` when it opens a log and throws
`InvalidOperationException: No current row` if the row is missing, which reaches
the operator as "A runtime error occurred".

So the definition row is written whenever a contest is opened, not only when it
is created — a log made before this was understood gets its row the next time it
is opened. `ContestDefinitions.For` builds the row from the contest's own rules:
the display and Cabrillo names, the mode, the dupe type and the multiplier
names.

## The overlay category cannot be empty

An empty `ContestInstance.OverlayCategory` is answered with "Invalid Overlay
Category:" and the log will not open. An entry with no overlay says `N/A`.

N1MM's list is not the Cabrillo specification's list. N1MM offers:

    N/A, ROOKIE, BAND-LIMITED, TB-WIRES, OVER-50, HQ, NOVICE-TECH, EXPERT

so that is what the contest dialog offers.

## The sent exchange omits the report

N1MM's contest dialog says "Omit RST: CQWW: 05". `SentExchange` for CQ WW is
`14`, not `599 14`; for a serial number contest it is `001`. The report is fixed
for the whole contest and the entry window fills it in per contact.

## Getting the schema in the first place

N1MM ships no template database. `ham.s3db` is built at run time by applying SQL
migration files that N1MM writes out from string resources inside
`N1MMLogger.net.exe`. To read them: decompile the executable, parse
`N1MMLogger.Net.Resources.resx`, and take the untyped `<data>` entries named
`DXLogDDL_0001_initial_schema_and_data` through `DXLogDDL_0004_updates`. The QSO
table is `DXLOG` and the current `PRAGMA user_version` is 4.

`src/Nonemm.Storage/Schema.sql` is that schema, flattened to the state version 4
leaves behind.

## One thing to avoid

Do not replace the database file under a running N1MM. It does not notice and
throws on the next read.

## A contact belongs to a ContestNR, not to the table key

`ContestInstance` has two numbers: `ContestID`, the table's primary key, and
`ContestNR`. `DXLOG.ContestNR` refers to the second one. N1MM's
`ContestInstance.SQLWhereString` reads:

    " ContestNR = " + this.ContestNR + " "

In a fresh log the two numbers match, so keying on either works. In a log N1MM
has been using for a while they drift apart. In one real log of 56284 contacts,
joining `DXLOG.ContestNR` to `ContestInstance.ContestID` disagreed with the
contact's own `ContestName` 52029 times; joining it to `ContestInstance.ContestNR`
disagreed 109 times.

So `ContestInstance.ContestNumber` here is `ContestNR`, and `ContestID` is
allocated separately when a contest is created.

## N1MM names a contest per mode

CQ WW is `CQWWCW`, `CQWWSSB` or `CQWWRTTY`, never plain `CQWW`. The full list
lives in the `Contest` table of any N1MM database. Nonemm writes the same names,
and `N1mmContestNames` turns one back into a contest and a mode when a log is
opened. The name carries the mode, so it beats whatever `ModeCategory` says.

Older N1MM versions wrote the CW running of CQ WW as plain `CQWW`. That name is
still in the registry, so those logs open.

## Which column an exchange lands in

N1MM keeps the received exchange of ARRL DX, IARU and WAE in `Sect`, not in
`Exchange1`, whatever the entry window calls the box. A contest that reads the
wrong column scores every contact as if the operator had typed nothing, so the
rule reads the column N1MM writes and the entry window points its box at the
same place.

N1MM also writes a single space into a text column it has nothing for, so
`Continent` comes back as `" "` rather than empty. Reading it as a value rather
than as empty makes every contact look like another continent. The store trims
what it reads.

## Scoring checked against a real log

`om5m.s3db` in the repo root is a station's own N1MM log: 78 contest instances
from 2019 to 2026, 57,000 contacts, 28 contest names. Replaying it is how the
scoring rules are checked — every contact is scored again from our rules and
compared with the points and multiplier flags N1MM wrote.

29 of the 37 instances whose contest we have rules for agree on every contact
and on the totals. What the check found and fixed:

| What | Was |
|---|---|
| ARRL DX and IARU read the wrong column | no multipliers at all, and IARU scored every contact 1 point |
| a stored `" "` was read as a value | 181 contacts in one log scored as another continent |
| the Canadian area lists | ARRL DX and CQ WW RTTY count the 14 areas N1MM calls `48SDC14P`, Newfoundland apart from Labrador, and the postal codes map onto them |
| a maritime mobile scored nothing | it is scored from the call it signs, which is the country N1MM logs for it |
| a call the country file cannot place brought no multiplier | it counts, with an empty value, and all such calls share the one multiplier per band |
| a contact in a mode the contest does not run | scored as if it were in the contest; N1MM scores it zero and keeps its multiplier |

What still differs, and why. None of it is a rule:

- **The country file of the day.** A 2019 log holds calls that today's
  `wl_cty.dat` places elsewhere — `TO7O` was Mayotte then and is France now,
  China was not split by call area yet — and the multiplier moves to another
  contact with it. This is nearly all of the difference in the 2019 CQ WW SSB
  log and all of it in the 2021 ones.
- **Stale cached points.** N1MM caches points in the row and does not always
  work them out again after a callsign is corrected, so a handful of rows hold
  a number that its own rules do not produce. Two IARU rows and about six CQ WW
  rows across 57,000 contacts.
- **A one-contact log** whose contact also sits in another instance of the same
  contest.

### What N1MM does that the published rules do not say

Three of the fixes above follow N1MM rather than the rule as published, because
a log has to score the same in both programs:

- ARRL DX counts `NF` and `LB` as two multipliers. They are one province.
- A maritime mobile counts for the country of the call it signs. CQ WW says it
  counts for the zone alone.
- A callsign that places nowhere counts as a multiplier with an empty value.