fix(dxcc): /MM and /AM belong to no entity

RI1FJL/MM resolved to Franz Josef Land while the expedition was still sailing
there, telling the operator they had worked an entity they had not.

The old behaviour was deliberate — the comment read "strict DXCC says no
entity, but the log should still show the operator's country" — and that is
wrong for exactly this reason. A home country on a maritime mobile is not extra
information; it is a false claim about where the contact happened, and it is
the kind of false claim that gets a QSO submitted for an award it cannot win.

Trailing only. A LEADING "MM" is the Scotland prefix and "AM" is Spain, so
MM0ABC and AM5X keep their entities — getting that wrong would be a far larger
error than the one being fixed. /P, /M and /B are unaffected: a portable
station is still ashore.

In the cluster the column says "Maritime mobile — no DXCC" rather than going
blank, because blank is what an UNRESOLVED spot looks like and the two mean
opposite things — one is "we don't know yet", this is "there is nothing to
know". Display only: the QSO's own Country stays empty, since that field holds
a DXCC entity name and there is none.

app.go

@@ -17452,6 +17452,16 @@ func (a *App) ClusterSpotStatuses(spots []SpotQuery) []SpotStatus {
 		if a.dxcc == nil {
 			continue
 		}
+		// Say WHY a maritime/aeronautical mobile has no entity, rather than
+		// leaving the column blank — blank is what an unresolved spot looks like,
+		// and the two mean opposite things: one is "we don't know yet", this is
+		// "there is nothing to know, the station is at sea". Display only: the
+		// QSO's own Country stays empty, because it is a DXCC entity name and
+		// there is none.
+		if dxcc.IsMobileNoEntity(q.Call) {
+			out[i].Country = "Maritime mobile — no DXCC"
+			continue
+		}
 		m, ok := a.dxcc.Lookup(q.Call)
 		if !ok || m.Entity == nil {
 			continue

changelog.json

@@ -10,7 +10,8 @@
       "Station Control: the short and long path headings are repeated under the compass, at a readable size and clickable.",
       "Compact mode: the window now fits the entry strip instead of leaving a band of empty space below it.",
       "HRDLog: an ON AIR option publishes your live frequency, mode and rig on hrdlog.net.",
-      "ADIF: the county is exported as STATE,COUNTY as the standard requires, and a county imported that way now fills the state too."
+      "ADIF: the county is exported as STATE,COUNTY as the standard requires, and a county imported that way now fills the state too.",
+      "A /MM or /AM callsign no longer resolves to a country — RI1FJL/MM read as Franz Josef Land while the expedition was still sailing there."
     ],
     "fr": [
       "Cluster : « Masquer les contactés » ne masque plus un spot qui est un nouveau préfixe, comté, carré ou parc dans une contrée déjà faite.",
@@ -20,7 +21,8 @@
       "Contrôle station : les azimuts court et long chemin sont repris sous la boussole, lisibles et cliquables.",
       "Mode compact : la fenêtre épouse la bande de saisie au lieu de laisser une bande vide en dessous.",
       "HRDLog : une option ON AIR publie ta fréquence, ton mode et ta radio en direct sur hrdlog.net.",
-      "ADIF : le comté est exporté sous la forme ÉTAT,COMTÉ comme l exige le standard, et un comté importé ainsi remplit aussi l état."
+      "ADIF : le comté est exporté sous la forme ÉTAT,COMTÉ comme l exige le standard, et un comté importé ainsi remplit aussi l état.",
+      "Un indicatif en /MM ou /AM ne se résout plus en pays — RI1FJL/MM affichait Franz Josef Land alors que l expédition faisait encore route."
     ]
   },
   {

internal/dxcc/dxcc.go

@@ -132,6 +132,18 @@ func (db *DB) Entities() []*Entity {
 func (db *DB) Lookup(callsign string) (Match, bool) {
 	db.mu.RLock()
 	defer db.mu.RUnlock()
+	// Maritime and aeronautical mobile belong to NO entity, and that is not a
+	// technicality — the station is at sea or in the air. RI1FJL/MM resolved to
+	// Franz Josef Land while the expedition was still on its way there, telling
+	// the operator they had worked an entity they had not.
+	//
+	// The previous choice was deliberate ("the log should still show the
+	// operator's country") and it is wrong for exactly that reason: a home
+	// country here is not extra information, it is a false claim about where the
+	// contact happened.
+	if IsMobileNoEntity(callsign) {
+		return Match{}, false
+	}
 	call := normalizeCallsign(callsign)
 	if call == "" {
 		return Match{}, false
@@ -364,3 +376,22 @@ func replaceAreaDigit(call string, d byte) string {
 	}
 	return call
 }
+
+// IsMobileNoEntity reports a callsign DXCC assigns to no entity: a TRAILING
+// /MM (maritime mobile) or /AM (aeronautical mobile).
+//
+// Trailing only. A LEADING "MM" is the Scotland prefix and "AM" is Spain, so
+// MM0ABC and AM5X are ordinary calls — treating those as entity-less would be a
+// far larger error than the one this fixes.
+func IsMobileNoEntity(callsign string) bool {
+	s := strings.ToUpper(strings.TrimSpace(callsign))
+	i := strings.LastIndex(s, "/")
+	if i < 0 {
+		return false
+	}
+	switch s[i+1:] {
+	case "MM", "AM":
+		return true
+	}
+	return false
+}

internal/dxcc/maritime_test.go

@@ -0,0 +1,39 @@
+package dxcc
+
+import "testing"
+
+// /MM and /AM belong to NO DXCC entity: the station is at sea or in the air.
+//
+// This is not a technicality. RI1FJL/MM resolved to Franz Josef Land while the
+// expedition was still sailing there, which told the operator they had worked
+// an entity they had not.
+func TestMobileNoEntity(t *testing.T) {
+	for _, tc := range []struct {
+		call string
+		want bool
+	}{
+		{"RI1FJL/MM", true},
+		{"YB1SCY/AM", true},
+		{"ri1fjl/mm", true},
+		{" RI1FJL/MM ", true},
+		// A LEADING MM is Scotland and AM is Spain. Treating those as
+		// entity-less would be a far larger error than the one this fixes.
+		{"MM0ABC", false},
+		{"AM5X", false},
+		{"MM/F4BPO", false},
+		{"AM/DL1ABC", false},
+		// Other suffixes keep their entity — a portable station is still ashore.
+		{"F4BPO/P", false},
+		{"F4BPO/M", false},
+		{"4U1UN/B", false},
+		{"F4BPO", false},
+		// Only the LAST element counts: RI1FJL/MM/P is still maritime, and a
+		// call whose /MM is not final is not.
+		{"RI1FJL/MM/P", false},
+		{"", false},
+	} {
+		if got := IsMobileNoEntity(tc.call); got != tc.want {
+			t.Errorf("IsMobileNoEntity(%q) = %v, want %v", tc.call, got, tc.want)
+		}
+	}
+}