Check a .udc section multiplier against the list the file names

MultWindowType names the list N1MM validates a received section against,
and every exchange that was not all digits counted as a multiplier here.
Four of N1MM's lists are held now -- the ARRL sections, the US states,
the Canadian provinces and the 165 OK/OM districts, which came out of
N1MM's own exe -- and a file naming one of them counts only the values
on it. A file naming any of the hundred-odd others keeps the old rule.

The 2023 OK/OM DX log now scores contact for contact as N1MM did. Two
contacts in the 2026 log still differ: the district code is stored with
a trailing space, which N1MM matches against its list untrimmed, so it
counts no multiplier where this counts one.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RoGtneMQaz4M9w7Kk49AVD

tests/Nonemm.Contests.Tests/UdcScoringTests.cs

@@ -264,9 +264,8 @@ public class UdcScoringTests
 
     /// The received exchange of a contest where one side sends a section and
     /// the other a serial number lands in the same column, and only the
-    /// section counts. N1MM checks it against the contest's section list; the
-    /// lists are not held here, so an exchange that is all digits is taken for
-    /// a serial number.
+    /// section counts. A file that names no list this program holds falls back
+    /// to taking an exchange of all digits for a serial number.
     [Fact]
     public void ASerialNumberIsNoSectionMultiplier()
     {
@@ -275,6 +274,23 @@ public class UdcScoringTests
         Assert.Single(LogFor(contest).Judge(TestLog.Contact("OM3XYZ", section: "NOV")).NewMultipliers);
     }
 
+    /// `MultWindowType` names the list N1MM checks the section against. `GZS`
+    /// is an OK/OM district and counts; `NOV` and the US state `MA` are not on
+    /// that list and count for neither program.
+    [Theory]
+    [InlineData("GZS", 1)]
+    [InlineData("NOV", 0)]
+    [InlineData("MA", 0)]
+    public void ASectionOffTheContestsListIsNoMultiplier(string section, int expected) =>
+        Assert.Equal(
+            expected,
+            LogFor(Contest(
+                    "MultSqlString=Section",
+                    "IsMultPer=1",
+                    "MultWindowType=OKOMDX"))
+                .Judge(TestLog.Contact("OM3XYZ", section: section))
+                .NewMultipliers.Count);
+
     /// Published files hold `Country` in this key; the UDC editor puts
     /// `CountryPrefix` there.
     [Fact]