diff --git a/StarterNG.Tests/ScenerySyntaxTests.cs b/StarterNG.Tests/ScenerySyntaxTests.cs
index 39fede4..6397a57 100644
--- a/StarterNG.Tests/ScenerySyntaxTests.cs
+++ b/StarterNG.Tests/ScenerySyntaxTests.cs
@@ -273,7 +273,7 @@ public class ScenerySyntaxTests
             include koniec.scm
             """;
 
-        var scenery = TestScenery.Parser().Parse("scenery/x.scn", scn, _ => true);
+        var scenery = TestScenery.Parser().Parse("scenery/x.scn", scn, new SceneryFileLookup(_ => true));
 
         Assert.Empty(scenery.Faults);
         Assert.Equal("td/rozklad", Assert.Single(scenery.Trainsets).Name);
@@ -326,7 +326,7 @@ public class ScenerySyntaxTests
             endoptional
             """;
 
-        var faults = TestScenery.Parser().Parse("scenery/x.scn", scn, name => name is "tory.scm" or "budynek.inc").Faults;
+        var faults = TestScenery.Parser().Parse("scenery/x.scn", scn, new SceneryFileLookup(name => name is "tory.scm" or "budynek.inc")).Faults;
 
         Assert.Equal((SceneryFaultKind.MissingInclude, "x.scn", 2, null, "brak.scm"), Seen(Assert.Single(faults)));
     }
@@ -378,4 +378,58 @@ public class ScenerySyntaxTests
         Assert.Equal(sbt, scenery.HasCompanionTimetable);
         Assert.Equal(sbt ? 0 : 1, scenery.Faults.Count);
     }
+
+    private static IReadOnlyList<SceneryFault> TerrainFaults(string scn, bool sbt, params string[] onDisk)
+    {
+        var files = new InMemoryFileSystem(caseSensitive: true).WithLegacyFile("game/scenery/Mapa.scn", scn);
+        if (sbt)
+            files.WithFile("game/scenery/mapa.sbt", "EU07");
+        foreach (string file in onDisk)
+            files.WithFile("game/scenery/" + file, "");
+        return TestScenery.Repository(files).Load("game/scenery/Mapa.scn")!.Faults;
+    }
+
+    [Theory]
+    [InlineData("Teren/Mapa.txtf")]
+    [InlineData("teren/mapa.btf")]
+    [InlineData("TEREN/MAPA.BTF")]
+    public void A_terrain_file_found_as_text_or_binary_is_no_fault(string onDisk) =>
+        Assert.Empty(TerrainFaults("terrain teren/mapa.txtf endterrain\nFirstInit\n", sbt: false, onDisk));
+
+    [Fact]
+    public void A_terrain_file_missing_both_ways_is_reported_but_an_sbt_named_with_it_is_not()
+    {
+        var faults = TerrainFaults("// teren\nterrain teren/mapa.btf teren/stara.sbt\nendterrain\nFirstInit\n", sbt: false);
+
+        Assert.Equal((SceneryFaultKind.MissingTerrainFile, "Mapa.scn", 2, null, "teren/mapa.btf"),
+                     Seen(Assert.Single(faults)));
+    }
+
+    [Fact]
+    public void A_terrain_file_takes_the_place_of_the_sbt_so_terrain_includes_are_read_after_all()
+    {
+        var faults = TerrainFaults("terrain teren/mapa.txtf endterrain\ninclude nmt/brak_ter.scm end\nFirstInit\n",
+                                   sbt: true, "teren/mapa.txtf");
+
+        Assert.Equal((SceneryFaultKind.MissingInclude, "Mapa.scn", 2, null, "nmt/brak_ter.scm"),
+                     Seen(Assert.Single(faults)));
+    }
+
+    [Theory]
+    [InlineData("include nmt/brak_ter.scm end\nterrain teren/mapa.txtf endterrain\nFirstInit\n", 2)]
+    [InlineData("node -1 0 t1 triangles trawa\n0 0 0 0 0 0 0 0 end\nendtri\nterrain teren/mapa.txtf endterrain\nFirstInit\n", 4)]
+    [InlineData("node -1 -1 t1 model 0 0 0 0 teren.t3d none endmodel\nterrain teren/mapa.txtf endterrain\nFirstInit\n", 2)]
+    [InlineData("FirstInit\nterrain teren/mapa.txtf endterrain\n", 2)]
+    public void A_terrain_file_behind_what_the_sbt_already_gave_is_passed_over(string scn, int line)
+    {
+        var faults = TerrainFaults(scn, sbt: true, "teren/mapa.txtf");
+
+        Assert.Equal((SceneryFaultKind.TerrainFileBehindSbt, "Mapa.scn", line, null, "teren/mapa.txtf"),
+                     Seen(Assert.Single(faults)));
+    }
+
+    [Fact]
+    public void A_model_not_of_the_terrain_leaves_the_sbt_free_to_give_way() =>
+        Assert.Empty(TerrainFaults("node 500 0 m1 model 0 0 0 0 dom.t3d none endmodel\nterrain teren/mapa.txtf endterrain\nFirstInit\n",
+                                   sbt: true, "teren/mapa.txtf"));
 }
diff --git a/StarterNG/Domain/Sceneries/SceneryFault.cs b/StarterNG/Domain/Sceneries/SceneryFault.cs
index 1b4f5f7..6b607d5 100644
--- a/StarterNG/Domain/Sceneries/SceneryFault.cs
+++ b/StarterNG/Domain/Sceneries/SceneryFault.cs
@@ -61,6 +61,19 @@ public enum SceneryFaultKind
     /// <summary>An include whose file is not there; <see cref="SceneryFault.Token"/> names it.</summary>
     MissingInclude,
 
+    /// <summary>
+    /// A terrain file named by a terrain directive whose text (.txtf) and binary
+    /// file (.btf) are both missing; <see cref="SceneryFault.Token"/> names it.
+    /// </summary>
+    MissingTerrainFile,
+
+    /// <summary>
+    /// A terrain file the simulator passes over: the scenery's terrain comes from its
+    /// .sbt, which something before the directive was already taken from;
+    /// <see cref="SceneryFault.Token"/> names it.
+    /// </summary>
+    TerrainFileBehindSbt,
+
     /// <summary>An include with no <c>end</c>, which swallows what follows it.</summary>
     IncludeNotClosed,
 
diff --git a/StarterNG/Domain/Sceneries/ScenerySyntax.cs b/StarterNG/Domain/Sceneries/ScenerySyntax.cs
index 87ee063..cdfe72e 100644
--- a/StarterNG/Domain/Sceneries/ScenerySyntax.cs
+++ b/StarterNG/Domain/Sceneries/ScenerySyntax.cs
@@ -5,6 +5,14 @@ using System.Linq;
 
 namespace StarterNG.Domain.Sceneries;
 
+/// <summary>What the simulator finds of the files a scenery names.</summary>
+/// <param name="Opens">Whether it opens a file of the scenery folder, named as the scenery names it.</param>
+/// <param name="HasSbt">
+/// Whether the scenery has its own .sbt: while that is in use, its terrain includes
+/// (<c>_ter.scm</c>) and terrain geometry are passed over, the .sbt holding them.
+/// </param>
+public sealed record SceneryFileLookup(Func<string, bool> Opens, bool HasSbt = false);
+
 /// <summary>
 /// Goes through a scenery's text for the parts the starter reads - trainsets,
 /// vehicles, includes - finding where each trainset and loose vehicle is, and
@@ -29,17 +37,17 @@ public static class ScenerySyntax
 
     /// <param name="text">The scenery's text, its includes put in place.</param>
     /// <param name="file">The scenery's file name, for faults in its own text.</param>
-    /// <param name="opensInclude">
-    /// Whether the simulator opens an include, named as the include names it; null
-    /// leaves includes unchecked.
+    /// <param name="files">
+    /// What the simulator finds of the files the scenery names - includes and terrain
+    /// files; null leaves them unchecked.
     /// </param>
-    public static Result Scan(string text, string file, Func<string, bool>? opensInclude = null)
+    public static Result Scan(string text, string file, SceneryFileLookup? files = null)
     {
         string code = SceneryCode.Mask(text, out int unclosed);
         var tokens = SceneryCode.Tokens(code);
         var lines = new SceneryLines(text, file);
 
-        var simulator = new Reading(tokens, lines, opensInclude, asSimulator: true);
+        var simulator = new Reading(tokens, lines, files, asSimulator: true);
         simulator.Run();
         var author = new Reading(tokens, lines, null, asSimulator: false);
         author.Run();
@@ -110,8 +118,14 @@ public static class ScenerySyntax
     }
 
     private sealed class Reading(
-        List<SceneryCode.Token> tokens, SceneryLines lines, Func<string, bool>? opensInclude, bool asSimulator)
+        List<SceneryCode.Token> tokens, SceneryLines lines, SceneryFileLookup? files, bool asSimulator)
     {
+        // Whether the scenery's .sbt is in use, and whether the simulator passed over
+        // something of the text on its account already - or got past FirstInit - after
+        // which a terrain file can no longer take its place.
+        private bool _sbt = files?.HasSbt ?? false;
+        private bool _sbtTaken;
+
         public readonly List<(int Start, int End, string Name)> Trainsets = new();
         public readonly List<(int, int)> Loose = new();
         public readonly List<SceneryFault> Faults = new();
@@ -156,12 +170,20 @@ public static class ScenerySyntax
                 {
                     // Not a vehicle: only its kind is stepped over, what follows is its own.
                     if (i + 4 >= tokens.Count || !tokens[i + 4].Is("dynamic"))
+                    {
+                        if (_sbt && TerrainGeometry(i))
+                            _sbtTaken = true;
                         i += 4;
+                    }
                     else
                         i = Vehicle(i);
                 }
                 else if (token.Is("include"))
                     i = Include(i);
+                else if (token.Is("terrain") && asSimulator)
+                    i = Terrain(i);
+                else if (token.Is("firstinit"))
+                    _sbtTaken |= _sbt;
             }
 
             if (_open is { } last)
@@ -369,8 +391,13 @@ public static class ScenerySyntax
                 return stop < tokens.Count && tokens[stop].Is("end") ? stop : stop - 1;
             }
 
-            if (opensInclude is not null && Plain(name) && !opensInclude(name))
-                Fault(SceneryFaultKind.MissingInclude, token.Index, token: name);
+            if (files is not null && Plain(name))
+            {
+                if (_sbt && SimulatorNames.Lower(name).Contains("_ter.scm"))
+                    _sbtTaken = true;
+                else if (!files.Opens(name))
+                    Fault(SceneryFaultKind.MissingInclude, token.Index, token: name);
+            }
 
             // The simulator takes its parameters up to the word "end", written just so,
             // whatever comes before it.
@@ -383,6 +410,52 @@ public static class ScenerySyntax
             return last;
         }
 
+        /// <summary>
+        /// A terrain directive: the files it names up to <c>endterrain</c>. Of a terrain
+        /// file (.txtf, .btf) the simulator takes the text or the binary file of the same
+        /// name, whichever is there; an .sbt it passes over quietly when it cannot use it.
+        /// </summary>
+        private int Terrain(int at)
+        {
+            int end = at + 1;
+            while (end < tokens.Count && !tokens[end].Is("endterrain"))
+                end++;
+
+            for (int named = at + 1; named < end && files is not null; named++)
+            {
+                string name = tokens[named].Text;
+                string lower = SimulatorNames.Lower(name);
+                if (!Plain(name) || !(lower.EndsWith(".txtf") || lower.EndsWith(".btf")))
+                    continue;
+
+                string stem = name[..name.LastIndexOf('.')];
+                if (!files.Opens(stem + ".txtf") && !files.Opens(stem + ".btf"))
+                    Fault(SceneryFaultKind.MissingTerrainFile, tokens[named].Index, token: name);
+                else if (_sbtTaken)
+                    Fault(SceneryFaultKind.TerrainFileBehindSbt, tokens[named].Index, token: name);
+                else
+                    // The .sbt gives way: the terrain includes from here on are read after all.
+                    _sbt = false;
+            }
+            return Math.Min(end, tokens.Count - 1);
+        }
+
+        /// <summary>
+        /// Whether the node starting at the given word is terrain geometry, which an .sbt
+        /// in use holds in its place: triangles or lines, or a model shown from any distance.
+        /// </summary>
+        private bool TerrainGeometry(int at)
+        {
+            if (at + 4 >= tokens.Count)
+                return false;
+            var kind = tokens[at + 4];
+            if (kind.Is("model"))
+                return double.TryParse(tokens[at + 2].Text, NumberStyles.Float, CultureInfo.InvariantCulture,
+                                       out double nearest) && nearest < 0;
+            return kind.Is("triangles") || kind.Is("triangle_strip") || kind.Is("triangle_fan") ||
+                   kind.Is("lines") || kind.Is("line_strip") || kind.Is("line_loop");
+        }
+
         // A vehicle with no trainset around it, written as within one - offset, crew,
         // coupling - where its track, offset and crew belong.
         private bool TrainsetStyle(int at) =>
diff --git a/StarterNG/Infrastructure/Sceneries/SceneryParser.cs b/StarterNG/Infrastructure/Sceneries/SceneryParser.cs
index f8072ba..c663355 100644
--- a/StarterNG/Infrastructure/Sceneries/SceneryParser.cs
+++ b/StarterNG/Infrastructure/Sceneries/SceneryParser.cs
@@ -20,11 +20,11 @@ public sealed class SceneryParser
         _random = random;
     }
 
-    /// <param name="opensInclude">
-    /// Whether the simulator opens an include, as the include names it; null leaves
-    /// includes unchecked.
+    /// <param name="files">
+    /// What the simulator finds of the files the scenery names; null leaves them
+    /// unchecked.
     /// </param>
-    public Scenery Parse(string path, string content, Func<string, bool>? opensInclude = null)
+    public Scenery Parse(string path, string content, SceneryFileLookup? files = null)
     {
         string original = content;
 
@@ -38,7 +38,7 @@ public sealed class SceneryParser
 
         // Read from the text with its optional includes blanked, which keeps every
         // place where it was, so a fault's line is the line in the file.
-        var syntax = ScenerySyntax.Scan(content, System.IO.Path.GetFileName(path), opensInclude);
+        var syntax = ScenerySyntax.Scan(content, System.IO.Path.GetFileName(path), files);
         var faults = syntax.Faults.ToList();
         var inlined = SceneryIncludes.Ranges(content);
 
diff --git a/StarterNG/Infrastructure/Sceneries/SceneryRepository.cs b/StarterNG/Infrastructure/Sceneries/SceneryRepository.cs
index 229d59a..a077dc6 100644
--- a/StarterNG/Infrastructure/Sceneries/SceneryRepository.cs
+++ b/StarterNG/Infrastructure/Sceneries/SceneryRepository.cs
@@ -7,7 +7,6 @@ using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
 using StarterNG.Application.Abstractions;
-using StarterNG.Domain;
 using StarterNG.Domain.Sceneries;
 using StarterNG.Infrastructure.Adapters;
 
@@ -78,10 +77,9 @@ public sealed class SceneryRepository : ISceneryRepository
             var encodings = new Dictionary<string, Encoding>(StringComparer.Ordinal);
 
             // With its own .sbt the scenery's terrain comes from it, and the simulator
-            // passes its terrain includes over without opening them.
+            // passes its terrain includes over without opening them - unless a terrain
+            // file takes its place.
             bool binaryTerrain = Opens(Path.GetFileNameWithoutExtension(path) + ".sbt");
-            bool OpensInclude(string name) =>
-                Opens(name) || (binaryTerrain && SimulatorNames.Lower(name).Contains("_ter.scm"));
 
             (string File, string Text)? ReadInclude(string name)
             {
@@ -98,7 +96,7 @@ public sealed class SceneryRepository : ISceneryRepository
 
             string own = LegacyText.Decode(_files.ReadAllBytes(path), out var ownEncoding);
             string text = SceneryIncludes.Inline(own, ReadInclude);
-            var scenery = _parser.Parse(path, text, OpensInclude);
+            var scenery = _parser.Parse(path, text, new SceneryFileLookup(Opens, binaryTerrain));
             scenery.HasCompanionTimetable = binaryTerrain;
             scenery.Sources = sources;
             scenery.TextEncoding = ownEncoding;
diff --git a/StarterNG/startercfg/lang/cz.xml b/StarterNG/startercfg/lang/cz.xml
index 64df1b5..a9f8073 100644
--- a/StarterNG/startercfg/lang/cz.xml
+++ b/StarterNG/startercfg/lang/cz.xml
@@ -742,6 +742,8 @@
     <String key="SyntaxVehicleOutsideTrainset">Vozidlo {0} stojí mimo soupravu: chybí záhlaví trainset?</String>
     <String key="SyntaxNotANumber">{0}: „{1}“ místo čísla</String>
     <String key="SyntaxMissingInclude">Soubor {1} nenalezen (include)</String>
+    <String key="SyntaxMissingTerrainFile">Soubor terénu {1} nenalezen, ani .txtf, ani .btf (terrain)</String>
+    <String key="SyntaxTerrainFileBehindSbt">Soubor terénu {1} ignorován: terén už pochází ze souboru .sbt scenérie</String>
     <String key="SyntaxIncludeNotClosed">include {1} bez end</String>
     <String key="SyntaxTrainsetUnreadable">Soupravu {0} se nepodařilo načíst</String>
     <String key="SyntaxVehicleUnreadable">Vozidlo {0} se nepodařilo načíst</String>
diff --git a/StarterNG/startercfg/lang/en.xml b/StarterNG/startercfg/lang/en.xml
index 3e1c383..df69ee9 100644
--- a/StarterNG/startercfg/lang/en.xml
+++ b/StarterNG/startercfg/lang/en.xml
@@ -772,6 +772,8 @@
     <String key="SyntaxVehicleOutsideTrainset">Vehicle {0} stands outside a trainset: header missing?</String>
     <String key="SyntaxNotANumber">{0}: “{1}” instead of a number</String>
     <String key="SyntaxMissingInclude">File {1} not found (include)</String>
+    <String key="SyntaxMissingTerrainFile">Terrain file {1} not found, neither .txtf nor .btf (terrain)</String>
+    <String key="SyntaxTerrainFileBehindSbt">Terrain file {1} ignored: the terrain already comes from the .sbt of the scenery</String>
     <String key="SyntaxIncludeNotClosed">include {1} without end</String>
     <String key="SyntaxTrainsetUnreadable">Trainset {0} could not be read</String>
     <String key="SyntaxVehicleUnreadable">Vehicle {0} could not be read</String>
diff --git a/StarterNG/startercfg/lang/hu.xml b/StarterNG/startercfg/lang/hu.xml
index d7286f1..9fb85a4 100644
--- a/StarterNG/startercfg/lang/hu.xml
+++ b/StarterNG/startercfg/lang/hu.xml
@@ -742,6 +742,8 @@
     <String key="SyntaxVehicleOutsideTrainset">A(z) {0} jármű szerelvényen kívül áll: hiányzik a trainset fejléc?</String>
     <String key="SyntaxNotANumber">{0}: „{1}” szám helyett</String>
     <String key="SyntaxMissingInclude">A(z) {1} fájl nem található (include)</String>
+    <String key="SyntaxMissingTerrainFile">A(z) {1} terepfájl nem található, sem .txtf, sem .btf (terrain)</String>
+    <String key="SyntaxTerrainFileBehindSbt">A(z) {1} terepfájl kimarad: a terep már a díszlet .sbt fájljából jön</String>
     <String key="SyntaxIncludeNotClosed">include {1} end nélkül</String>
     <String key="SyntaxTrainsetUnreadable">A(z) {0} szerelvényt nem sikerült beolvasni</String>
     <String key="SyntaxVehicleUnreadable">A(z) {0} járművet nem sikerült beolvasni</String>
diff --git a/StarterNG/startercfg/lang/pl.xml b/StarterNG/startercfg/lang/pl.xml
index 7e2df79..190a4f3 100644
--- a/StarterNG/startercfg/lang/pl.xml
+++ b/StarterNG/startercfg/lang/pl.xml
@@ -769,6 +769,8 @@
     <String key="SyntaxVehicleOutsideTrainset">Pojazd {0} stoi poza składem: brak nagłówka trainset?</String>
     <String key="SyntaxNotANumber">{0}: „{1}” zamiast liczby</String>
     <String key="SyntaxMissingInclude">Brak pliku {1} (include)</String>
+    <String key="SyntaxMissingTerrainFile">Brak pliku terenu {1}, ani .txtf, ani .btf (terrain)</String>
+    <String key="SyntaxTerrainFileBehindSbt">Plik terenu {1} pominięty: teren pochodzi już z pliku .sbt scenerii</String>
     <String key="SyntaxIncludeNotClosed">include {1} bez end</String>
     <String key="SyntaxTrainsetUnreadable">Nie udało się odczytać składu {0}</String>
     <String key="SyntaxVehicleUnreadable">Nie udało się odczytać pojazdu {0}</String>
diff --git a/StarterNG/startercfg/lang/ru.xml b/StarterNG/startercfg/lang/ru.xml
index 280351e..ab65bd5 100644
--- a/StarterNG/startercfg/lang/ru.xml
+++ b/StarterNG/startercfg/lang/ru.xml
@@ -742,6 +742,8 @@
     <String key="SyntaxVehicleOutsideTrainset">Транспорт {0} стоит вне состава: нет заголовка trainset?</String>
     <String key="SyntaxNotANumber">{0}: «{1}» вместо числа</String>
     <String key="SyntaxMissingInclude">Файл {1} не найден (include)</String>
+    <String key="SyntaxMissingTerrainFile">Файл рельефа {1} не найден, ни .txtf, ни .btf (terrain)</String>
+    <String key="SyntaxTerrainFileBehindSbt">Файл рельефа {1} пропущен: рельеф уже берётся из файла .sbt сценария</String>
     <String key="SyntaxIncludeNotClosed">include {1} без end</String>
     <String key="SyntaxTrainsetUnreadable">Не удалось прочитать состав {0}</String>
     <String key="SyntaxVehicleUnreadable">Не удалось прочитать единицу {0}</String>