diff --git a/Array.mqh b/Array.mqh
index 8612c60d4..9ac485b46 100644
--- a/Array.mqh
+++ b/Array.mqh
@@ -20,9 +20,10 @@
  *
  */
 
-// Prevents processing this includes file for the second time.
-#ifndef ARRAY_MQH
-#define ARRAY_MQH
+#ifndef __MQL__
+// Allows the preprocessor to include a header file when it is needed.
+#pragma once
+#endif
 
 // Defines.
 #ifndef MODE_ASCEND
@@ -38,6 +39,26 @@
 #define WHOLE_ARRAY 0
 #endif
 
+/**
+ * Reference to the array.
+ *
+ * @usage
+ *   ARRAY_REF(<type of the array items>, <name of the variable>)
+ */
+#ifdef __MQL__
+#define ARRAY_REF(T, N) REF(T) N
+#endif
+
+/**
+ * Array definition.
+ *
+ * @usage
+ *   ARRAY(<type of the array items>, <name of the variable>)
+ */
+#ifdef __MQL__
+#define ARRAY(T, N) T N[];
+#endif
+
 /*
  * Class to provide methods to deal with arrays.
  */
@@ -698,7 +719,19 @@ class Array {
    */
   template <typename X>
   static int ArrayMinimum(const ARRAY_REF(X, _array), int _start = 0, int _count = WHOLE_ARRAY) {
+#ifdef __MQL__
     return ::ArrayMinimum(_array);
+#else
+    int _peak_index = 0;
+
+    for (int i = 1; i < ArraySize(_array); ++i) {
+      if (_array[i] < _array[_peak_index]) {
+        _peak_index = i;
+      }
+    }
+
+    return _peak_index;
+#endif
   }
 
   /**
@@ -718,8 +751,20 @@ class Array {
    * - https://www.mql5.com/en/docs/array/arraymaximum
    */
   template <typename X>
-  static int ArrayMaximum(const ARRAY_REF(X, array), int start = 0, int count = WHOLE_ARRAY) {
-    return ::ArrayMaximum(array);
+  static int ArrayMaximum(const ARRAY_REF(X, _array), int start = 0, int count = WHOLE_ARRAY) {
+#ifdef __MQL__
+    return ::ArrayMaximum(_array);
+#else
+    int _peak_index = 0;
+
+    for (int i = 1; i < ArraySize(_array); ++i) {
+      if (_array[i] > _array[_peak_index]) {
+        _peak_index = i;
+      }
+    }
+
+    return _peak_index;
+#endif
   }
 
   /**
@@ -739,4 +784,3 @@ class Array {
     return ::ArraySize(array);
   }
 };
-#endif // ARRAY_MQH
diff --git a/Bar.struct.h b/Bar.struct.h
index bbd8f5a42..06e0969a8 100644
--- a/Bar.struct.h
+++ b/Bar.struct.h
@@ -30,11 +30,14 @@
 #pragma once
 #endif
 
+// Forward class declaration.
+class Serializer;
+
 // Includes.
 #include "Bar.enum.h"
 #include "Chart.enum.h"
 #include "ISerializable.h"
-#include "Serializer.mqh"
+#include "Serializer.enum.h"
 #include "SerializerNode.enum.h"
 
 /* Struct for storing OHLC values. */
@@ -216,6 +219,8 @@ struct BarOHLC
   string ToCSV() { return StringFormat("%d,%g,%g,%g,%g", time, open, high, low, close); }
 };
 
+#include "Serializer.mqh"
+
 /* Method to serialize BarOHLC structure. */
 SerializerNodeType BarOHLC::Serialize(Serializer &s) {
   // s.Pass(this, "time", TimeToString(time));
diff --git a/Chart.mqh b/Chart.mqh
index 63df2f792..5865b0c75 100644
--- a/Chart.mqh
+++ b/Chart.mqh
@@ -88,11 +88,11 @@ struct MqlRates {
 class Chart : public Market {
  protected:
   // Structs.
-  ChartEntry chart_saves[];
+  ARRAY(ChartEntry, chart_saves);
   ChartParams cparams;
 
   // Stores information about the prices, volumes and spread.
-  MqlRates rates[];
+  ARRAY(MqlRates, rates);
   ChartEntry c_entry;
 
   // Stores indicator instances.
@@ -452,7 +452,7 @@ class Chart : public Market {
     long StartBar = 0;
     long StartGenM1 = 0;
     long HistoryTotal = 0;
-    datetime modeling_start_time = D'1971.01.01 00:00';
+    datetime modeling_start_time = DATETIME_LITERAL(1971.01.01 00:00);
 
     if (TimePr == NULL) TimePr = (ENUM_TIMEFRAMES)Period();
     if (TimePr == PERIOD_M1) TimeNearPr = PERIOD_M1;
diff --git a/Convert.mqh b/Convert.mqh
index 8fd41f530..a280e2b3f 100644
--- a/Convert.mqh
+++ b/Convert.mqh
@@ -26,7 +26,6 @@
 
 // Includes.
 #include "Account.enum.h"
-#include "Math.h"
 #include "SymbolInfo.static.h"
 #include "Order.enum.h"
 
@@ -357,60 +356,6 @@ public:
   static void DoubleToType(double _value, float& _out) { _out = (float)_value; }
   static void DoubleToType(double _value, double& _out) { _out = (double)_value; }
   static void DoubleToType(double _value, string& _out) { _out = _value ? "1" : "0"; }
-
-  /**
-   * Converts MqlParam struct to double.
-   *
-   * @todo: Move to Data class.
-   */
-  static double MqlParamToDouble(MqlParam& param) {
-    switch (param.type) {
-      case TYPE_BOOL:
-        return param.integer_value ? 1 : 0;
-      case TYPE_INT:
-      case TYPE_LONG:
-      case TYPE_UINT:
-      case TYPE_ULONG:
-        return (double)param.integer_value;
-      case TYPE_DOUBLE:
-      case TYPE_FLOAT:
-        return param.double_value;
-      case TYPE_CHAR:
-      case TYPE_STRING:
-      case TYPE_UCHAR:
-        return StringToDouble(param.string_value);
-    }
-    return DBL_MIN;
-  }
-
-  /**
-   * Converts MqlParam struct to integer.
-   *
-   * @todo: Move to Data class.
-   */
-  static long MqlParamToInteger(MqlParam& param) {
-    switch (param.type) {
-      case TYPE_BOOL:
-        return param.integer_value ? 1 : 0;
-      case TYPE_DATETIME:
-      case TYPE_INT:
-      case TYPE_LONG:
-      case TYPE_UINT:
-      case TYPE_ULONG:
-      case TYPE_SHORT:
-        return param.integer_value;
-      case TYPE_DOUBLE:
-      case TYPE_FLOAT:
-        return (int) param.double_value;
-      case TYPE_CHAR:
-      case TYPE_COLOR:
-      case TYPE_STRING:
-      case TYPE_UCHAR:
-        return StringToInteger(param.string_value);
-    }
-    return INT_MIN;
-  }
-
 };
 
 
diff --git a/Data.struct.h b/Data.struct.h
index 1ce505a7b..ae7cde6f4 100644
--- a/Data.struct.h
+++ b/Data.struct.h
@@ -36,6 +36,7 @@ struct MqlParam;
 
 // Includes.
 #include "Data.enum.h"
+#include "Serializer.enum.h"
 #include "SerializerNode.enum.h"
 
 #ifndef __MQL__
@@ -106,6 +107,59 @@ struct MqlParam {
 };
 #endif
 
+/**
+ * Converts MqlParam struct to integer.
+ *
+ * @todo: Move to Data class.
+ */
+long MqlParamToInteger(MqlParam &param) {
+  switch (param.type) {
+    case TYPE_BOOL:
+      return param.integer_value ? 1 : 0;
+    case TYPE_DATETIME:
+    case TYPE_INT:
+    case TYPE_LONG:
+    case TYPE_UINT:
+    case TYPE_ULONG:
+    case TYPE_SHORT:
+      return param.integer_value;
+    case TYPE_DOUBLE:
+    case TYPE_FLOAT:
+      return (int)param.double_value;
+    case TYPE_CHAR:
+    case TYPE_COLOR:
+    case TYPE_STRING:
+    case TYPE_UCHAR:
+      return StringToInteger(param.string_value);
+  }
+  return INT_MIN;
+}
+
+  /**
+ * Converts MqlParam struct to double.
+ *
+ * @todo: Move to Data class.
+ */
+static double MqlParamToDouble(MqlParam &param) {
+  switch (param.type) {
+    case TYPE_BOOL:
+      return param.integer_value ? 1 : 0;
+    case TYPE_INT:
+    case TYPE_LONG:
+    case TYPE_UINT:
+    case TYPE_ULONG:
+      return (double)param.integer_value;
+    case TYPE_DOUBLE:
+    case TYPE_FLOAT:
+      return param.double_value;
+    case TYPE_CHAR:
+    case TYPE_STRING:
+    case TYPE_UCHAR:
+      return StringToDouble(param.string_value);
+  }
+  return DBL_MIN;
+}
+
 /**
  * Struct to provide multitype data parameters.
  *
diff --git a/DateTime.enum.h b/DateTime.enum.h
index 73e7facbe..b21cc9a20 100644
--- a/DateTime.enum.h
+++ b/DateTime.enum.h
@@ -30,6 +30,12 @@
 #pragma once
 #endif
 
+#ifdef __MQL__
+#define DATETIME_LITERAL(STR) D'##STR##'
+#else
+#define DATETIME_LITERAL(STR) D"##STR##"
+#endif
+
 /* Defines datetime conditions. */
 enum ENUM_DATETIME_CONDITION {
   DATETIME_COND_IS_PEAK_HOUR = 1,  // On peak hour
diff --git a/Math.h b/Math.h
index 3ecf23a96..16ab0e763 100644
--- a/Math.h
+++ b/Math.h
@@ -20,9 +20,10 @@
  *
  */
 
-// Prevents processing this includes file for the second time.
-#ifndef MATH_H
-#define MATH_H
+#ifndef __MQL__
+// Allows the preprocessor to include a header file when it is needed.
+#pragma once
+#endif
 
 // Includes.
 #include "Data.struct.h"
@@ -256,5 +257,3 @@ class Math {
     }
   }
 };
-
-#endif  // MATH_M
diff --git a/MqlTick.h b/MqlTick.h
new file mode 100644
index 000000000..241e807b5
--- /dev/null
+++ b/MqlTick.h
@@ -0,0 +1,48 @@
+//+------------------------------------------------------------------+
+//|                                                EA31337 framework |
+//|                                 Copyright 2016-2021, EA31337 Ltd |
+//|                                       https://github.com/EA31337 |
+//+------------------------------------------------------------------+
+
+/*
+ *  This file is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/**
+ * @file
+ * MqlTick structure.
+ */
+
+#ifndef __MQL__
+// Allows the preprocessor to include a header file when it is needed.
+#pragma once
+#endif
+
+#ifndef __MQL__
+/**
+ * Structure for storing the latest prices of the symbol.
+ * @docs
+ * https://www.mql5.com/en/docs/constants/structures/mqltick
+ */
+struct MqlTick {
+  datetime time;         // Time of the last prices update.
+  double ask;            // Current Ask price.
+  double bid;            // Current Bid price.
+  double last;           // Price of the last deal (last).
+  double volume_real;    // Volume for the current last price with greater accuracy.
+  long time_msc;         // Time of a price last update in milliseconds.
+  unsigned int flags;    // Tick flags.
+  unsigned long volume;  // Volume for the current last price.
+};
+#endif
diff --git a/Serializer.mqh b/Serializer.mqh
index cef2c45b1..26371304e 100644
--- a/Serializer.mqh
+++ b/Serializer.mqh
@@ -25,6 +25,7 @@
 #define SERIALIZER_MQH
 
 // Includes.
+#include "Convert.mqh"
 #include "Serializer.define.h"
 #include "Serializer.enum.h"
 #include "SerializerNode.mqh"
diff --git a/SymbolInfo.define.h b/SymbolInfo.define.h
index 92f8acb43..68ef4c107 100644
--- a/SymbolInfo.define.h
+++ b/SymbolInfo.define.h
@@ -27,7 +27,7 @@
 
 /* Defines */
 
-#ifndef __MQL4__
+#ifdef __MQL5__
 // --
 #define Point _Point
 #define Digits _Digits
diff --git a/SymbolInfo.struct.h b/SymbolInfo.struct.h
index d89112c08..addb386f5 100644
--- a/SymbolInfo.struct.h
+++ b/SymbolInfo.struct.h
@@ -32,26 +32,9 @@
 
 // Includes.
 #include "ISerializable.h"
+#include "MqlTick.h"
 #include "Serializer.mqh"
 
-#ifndef __MQL__
-/**
- * Structure for storing the latest prices of the symbol.
- * @docs
- * https://www.mql5.com/en/docs/constants/structures/mqltick
- */
-struct MqlTick {
-  datetime time;         // Time of the last prices update.
-  double ask;            // Current Ask price.
-  double bid;            // Current Bid price.
-  double last;           // Price of the last deal (last).
-  double volume_real;    // Volume for the current last price with greater accuracy.
-  long time_msc;         // Time of a price last update in milliseconds.
-  unsigned int flags;    // Tick flags.
-  unsigned long volume;  // Volume for the current last price.
-};
-#endif
-
 // Defines struct to store symbol data.
 struct SymbolInfoEntry
 #ifndef __MQL__
diff --git a/Terminal.mqh b/Terminal.mqh
index 4765e9729..5f87fd637 100644
--- a/Terminal.mqh
+++ b/Terminal.mqh
@@ -875,8 +875,8 @@ class Terminal : public Object {
    *   Returns true when the condition is met.
    */
   bool CheckCondition(ENUM_TERMINAL_CONDITION _cond, ARRAY_REF(DataParamEntry, _args)) {
-    long _arg1l = ArraySize(_args) > 0 ? Convert::MqlParamToInteger(_args[0]) : WRONG_VALUE;
-    long _arg2l = ArraySize(_args) > 1 ? Convert::MqlParamToInteger(_args[1]) : WRONG_VALUE;
+    long _arg1l = ArraySize(_args) > 0 ? MqlParamToInteger(_args[0]) : WRONG_VALUE;
+    long _arg2l = ArraySize(_args) > 1 ? MqlParamToInteger(_args[1]) : WRONG_VALUE;
     switch (_cond) {
       case TERMINAL_COND_IS_CONNECTED:
         return !IsConnected();
@@ -910,9 +910,9 @@ class Terminal : public Object {
    *   Returns true when the condition is met.
    */
   bool ExecuteAction(ENUM_TERMINAL_ACTION _action, ARRAY_REF(MqlParam, _args)) {
-    long _arg1l = ArraySize(_args) > 0 ? Convert::MqlParamToInteger(_args[0]) : WRONG_VALUE;
-    long _arg2l = ArraySize(_args) > 1 ? Convert::MqlParamToInteger(_args[1]) : WRONG_VALUE;
-    long _arg3l = ArraySize(_args) > 2 ? Convert::MqlParamToInteger(_args[2]) : WRONG_VALUE;
+    long _arg1l = ArraySize(_args) > 0 ? MqlParamToInteger(_args[0]) : WRONG_VALUE;
+    long _arg2l = ArraySize(_args) > 1 ? MqlParamToInteger(_args[1]) : WRONG_VALUE;
+    long _arg3l = ArraySize(_args) > 2 ? MqlParamToInteger(_args[2]) : WRONG_VALUE;
     switch (_action) {
       case TERMINAL_ACTION_CRASH:
         delete THIS_PTR;