diff --git a/ASTPlayground/Script.txt b/ASTPlayground/Script.txt
index 3e7bf70..09e0d2d 100644
--- a/ASTPlayground/Script.txt
+++ b/ASTPlayground/Script.txt
@@ -41,8 +41,8 @@
     (fn [len]
       (do
         ;; Konstanten vorberechnen
-        (def half-len (Round (/ len 2)))
-        (def sqrt-len (Round (sqrt len)))
+        (def half-len (round (/ len 2)))
+        (def sqrt-len (round (sqrt len)))
 
         ;; !!! WICHTIG !!!
         ;; HMA benötigt eine Glättung der Differenz. 
diff --git a/Src/AST/Myc.Ast.RTL.Core.pas b/Src/AST/Myc.Ast.RTL.Core.pas
index 7ba851c..7934fef 100644
--- a/Src/AST/Myc.Ast.RTL.Core.pas
+++ b/Src/AST/Myc.Ast.RTL.Core.pas
@@ -123,54 +123,54 @@ type
 
         // --- Math Functions ---
 
-        [TRtlExport('Abs', Pure)]
+        [TRtlExport('abs', Pure)]
         [AstDoc('Returns the absolute value of a number.')]
         [AstSignature('(number) -> number')]
         class function Abs(const Arg: TScalar): TScalar; static;
 
-        [TRtlExport('Round', Pure)]
+        [TRtlExport('round', Pure)]
         [AstDoc('Rounds a float to the nearest integer.')]
         [AstSignature('(number) -> number')]
         class function Round(const Arg: TScalar): TScalar; static;
 
-        [TRtlExport('Trunc', Pure)]
+        [TRtlExport('trunc', Pure)]
         [AstDoc('Returns the integer part of a float.')]
         [AstSignature('(number) -> number')]
         class function Trunc(const Arg: TScalar): TScalar; static;
 
-        [TRtlExport('Ceil', Pure)]
+        [TRtlExport('ceil', Pure)]
         [AstDoc('Returns the smallest integer >= the argument.')]
         [AstSignature('(number) -> number')]
         class function Ceil(const Arg: TScalar): TScalar; static;
 
-        [TRtlExport('Floor', Pure)]
+        [TRtlExport('floor', Pure)]
         [AstDoc('Returns the largest integer <= the argument.')]
         [AstSignature('(number) -> number')]
         class function Floor(const Arg: TScalar): TScalar; static;
 
-        [TRtlExport('Sign', Pure)]
+        [TRtlExport('sign', Pure)]
         [AstDoc('Returns -1 for negative, 1 for positive, 0 for zero.')]
         [AstSignature('(number) -> number')]
         class function Sign(const Arg: TScalar): TScalar; static;
 
-        [TRtlExport('Sqrt', Pure)]
+        [TRtlExport('sqrt', Pure)]
         [AstDoc('Returns the square root of a number.')]
         [AstSignature('(number) -> number')]
         class function Sqrt(const Arg: TScalar): TScalar; static;
 
-        [TRtlExport('Pow', Pure)]
+        [TRtlExport('pow', Pure)]
         [AstDoc('Returns Base raised to the power of Exponent.')]
         [AstSignature('(number, number) -> number')]
         class function Pow(const Args: TArray<TDataValue>): TDataValue; static;
 
         // --- DateTime ---
 
-        [TRtlExport('Now', Impure)]
+        [TRtlExport('now', Impure)]
         [AstDoc('Returns the current system timestamp.')]
         [AstSignature('() -> datetime')]
         class function Now(const Args: TArray<TDataValue>): TDataValue; static;
 
-        [TRtlExport('Date', Impure)]
+        [TRtlExport('date', Impure)]
         [AstDoc('Returns the current date or constructs a date from Y, M, D.')]
         [AstSignature('() -> datetime')]
         [AstSignature('(number, number, number) -> datetime')]
@@ -178,27 +178,27 @@ type
 
         // --- Functional / Series ---
 
-        [TRtlExport('Memoize', Pure)]
+        [TRtlExport('memoize', Pure)]
         [AstDoc('Creates a memoized version of a function for performance.')]
         [AstSignature('((any) -> any) -> ((any) -> any)')]
         class function Memoize(const Args: TArray<TDataValue>): TDataValue; static;
 
-        [TRtlExport('Map', Pure)]
+        [TRtlExport('map', Pure)]
         [AstDoc('Applies a function to every element of a series.')]
         [AstSignature('(series, (any) -> any) -> series')]
         class function Map(const Args: TArray<TDataValue>): TDataValue; static;
 
-        [TRtlExport('Reduce', Pure)]
+        [TRtlExport('reduce', Pure)]
         [AstDoc('Collapses a series into a single value using a reducer function.')]
         [AstSignature('(series, any, (any, any) -> any) -> any')]
         class function Reduce(const Args: TArray<TDataValue>): TDataValue; static;
 
-        [TRtlExport('Where', Pure)]
+        [TRtlExport('where', Pure)]
         [AstDoc('Filters a series based on a predicate function.')]
         [AstSignature('(series, (any) -> boolean) -> series')]
         class function Where(const Args: TArray<TDataValue>): TDataValue; static;
 
-        [TRtlExport('Any', Pure)]
+        [TRtlExport('any', Pure)]
         [AstDoc('Returns true if at least one element satisfies the predicate.')]
         [AstSignature('(series, (any) -> boolean) -> boolean')]
         class function Any(const Args: TArray<TDataValue>): TDataValue; static;
@@ -324,31 +324,31 @@ type
         [TRtlExport('not', Pure)]
         class function Not_Ordinal_Ordinal(A: Int64): Int64; static;
 
-        [TRtlExport('Abs', Pure)]
+        [TRtlExport('abs', Pure)]
         class function Abs_Ordinal_Ordinal(A: Int64): Int64; static;
-        [TRtlExport('Abs', Pure)]
+        [TRtlExport('abs', Pure)]
         class function Abs_Float_Float(A: Double): Double; static;
-        [TRtlExport('Round', Pure)]
+        [TRtlExport('round', Pure)]
         class function Round_Ordinal_Ordinal(A: Int64): Int64; static;
-        [TRtlExport('Round', Pure)]
+        [TRtlExport('round', Pure)]
         class function Round_Float_Ordinal(A: Double): Int64; static;
-        [TRtlExport('Trunc', Pure)]
+        [TRtlExport('trunc', Pure)]
         class function Trunc_Ordinal_Ordinal(A: Int64): Int64; static;
-        [TRtlExport('Trunc', Pure)]
+        [TRtlExport('trunc', Pure)]
         class function Trunc_Float_Ordinal(A: Double): Int64; static;
 
-        [TRtlExport('Sqrt', Pure)]
+        [TRtlExport('sqrt', Pure)]
         class function Sqrt_Ordinal_Float(A: Int64): Double; static;
-        [TRtlExport('Sqrt', Pure)]
+        [TRtlExport('sqrt', Pure)]
         class function Sqrt_Float_Float(A: Double): Double; static;
 
-        [TRtlExport('Pow', Pure)]
+        [TRtlExport('pow', Pure)]
         class function Pow_Ordinal_Ordinal_Float(A, B: Int64): Double; static;
-        [TRtlExport('Pow', Pure)]
+        [TRtlExport('pow', Pure)]
         class function Pow_Float_Float_Float(A, B: Double): Double; static;
-        [TRtlExport('Pow', Pure)]
+        [TRtlExport('pow', Pure)]
         class function Pow_Ordinal_Float_Float(A: Int64; B: Double): Double; static;
-        [TRtlExport('Pow', Pure)]
+        [TRtlExport('pow', Pure)]
         class function Pow_Float_Ordinal_Float(A: Double; B: Int64): Double; static;
     end;
 
diff --git a/Test/AST/Test.Myc.Ast.RTL.DateTime.pas b/Test/AST/Test.Myc.Ast.RTL.DateTime.pas
index 4a965ab..d06cbb3 100644
--- a/Test/AST/Test.Myc.Ast.RTL.DateTime.pas
+++ b/Test/AST/Test.Myc.Ast.RTL.DateTime.pas
@@ -65,7 +65,7 @@ var
     Expected: TDateTime;
 begin
     // Act
-    Res := FEnv.Run(TAstScript.Parse('(Date 2025 11 24)'));
+    Res := FEnv.Run(TAstScript.Parse('(date 2025 11 24)'));
 
     // Assert
     Assert.AreEqual(TDataValueKind.vkScalar, Res.Kind, 'Result should be scalar');
@@ -85,7 +85,7 @@ begin
     Sleep(1);
 
     // Act
-    Res := FEnv.Run(TAstScript.Parse('(Now)'));
+    Res := FEnv.Run(TAstScript.Parse('(now)'));
 
     After := System.SysUtils.Now;
 
@@ -103,7 +103,7 @@ var
     Res: TDataValue;
 begin
     // (> (Date y1 m1 d1) (Date y2 m2 d2))
-    Script := Format('(> (Date %d %d %d) (Date %d %d %d))', [Y1, M1, D1, Y2, M2, D2]);
+    Script := Format('(> (date %d %d %d) (date %d %d %d))', [Y1, M1, D1, Y2, M2, D2]);
 
     Res := FEnv.Run(TAstScript.Parse(Script));
 
@@ -120,7 +120,7 @@ var
     Res: TDataValue;
 begin
     // (= (Date 2023 10 10) (Date 2023 10 10))
-    Res := FEnv.Run(TAstScript.Parse('(= (Date 2023 10 10) (Date 2023 10 10))'));
+    Res := FEnv.Run(TAstScript.Parse('(= (date 2023 10 10) (date 2023 10 10))'));
 
     Assert.AreEqual(TScalar.TKind.Boolean, Res.AsScalar.Kind);
     Assert.AreEqual(Int64(1), Res.AsScalar.Value.AsInt64);
@@ -132,7 +132,7 @@ var
 begin
     // (if (Date 2023 1 1) "yes" "no")
     // Checks if IsTruthy correctly handles TKind.DateTime
-    Res := FEnv.Run(TAstScript.Parse('(if (Date 2023 1 1) "yes" "no")'));
+    Res := FEnv.Run(TAstScript.Parse('(if (date 2023 1 1) "yes" "no")'));
 
     Assert.AreEqual(TDataValueKind.vkText, Res.Kind);
     Assert.AreEqual('yes', Res.AsText);
@@ -151,7 +151,7 @@ begin
     InputDate := EncodeDate(2023, 11, 24);
     Expected := System.Round(InputDate);
 
-    Res := FEnv.Run(TAstScript.Parse('(Round (Date 2023 11 24))'));
+    Res := FEnv.Run(TAstScript.Parse('(round (date 2023 11 24))'));
 
     Assert.AreEqual(TScalar.TKind.Ordinal, Res.AsScalar.Kind);
     Assert.AreEqual(Expected, Res.AsScalar.Value.AsInt64);
diff --git a/Test/AST/Test.Myc.Ast.RTL.pas b/Test/AST/Test.Myc.Ast.RTL.pas
index 725bf05..89622fd 100644
--- a/Test/AST/Test.Myc.Ast.RTL.pas
+++ b/Test/AST/Test.Myc.Ast.RTL.pas
@@ -128,8 +128,8 @@ procedure TTestMycAstRTL.RTL_Registration_SymbolsArePresent;
 begin
     Assert.AreNotEqual(TAddressKind.akUnresolved, FScope.Resolve('div').Kind);
     Assert.AreNotEqual(TAddressKind.akUnresolved, FScope.Resolve('mod').Kind);
-    Assert.AreNotEqual(TAddressKind.akUnresolved, FScope.Resolve('Date').Kind);
-    Assert.AreNotEqual(TAddressKind.akUnresolved, FScope.Resolve('Round').Kind);
+    Assert.AreNotEqual(TAddressKind.akUnresolved, FScope.Resolve('date').Kind);
+    Assert.AreNotEqual(TAddressKind.akUnresolved, FScope.Resolve('round').Kind);
 end;
 
 procedure TTestMycAstRTL.RTL_Math_Float(const Op: string; A, B, Expected: Double);
@@ -164,7 +164,7 @@ procedure TTestMycAstRTL.RTL_Round_Works(A: Double; Expected: Int64);
 var
     res: TDataValue;
 begin
-    res := Call('Round', [ValF(A)]);
+    res := Call('round', [ValF(A)]);
     Assert.AreEqual(TScalar.TKind.Ordinal, res.AsScalar.Kind);
     Assert.AreEqual(Expected, res.AsScalar.Value.AsInt64);
 end;
@@ -192,7 +192,7 @@ var
 begin
     // 1. Test Date(Y, M, D)
     expectedDate := EncodeDate(2023, 10, 5);
-    d := Call('Date', [ValI(2023), ValI(10), ValI(5)]);
+    d := Call('date', [ValI(2023), ValI(10), ValI(5)]);
 
     Assert.AreEqual(TScalar.TKind.DateTime, d.AsScalar.Kind);
     Assert.AreEqual(expectedDate, d.AsScalar.Value.AsDouble, 0.001);