How to view internal function code?

<p id="isPasted">In MetaTrader, "internal code" is divided into two categories: the Standard Library (which is open and viewable) and Built-in Functions (which are compiled into the terminal's core and are not viewable).</p><p><strong>1. Viewing the Standard Library Code (.mqh files)</strong></p><p>The MQL4/MQL5 Standard Library consists of classes and functions written in MQL that you can freely read, modify, or copy.&nbsp;</p><ul><li>Location: Open the MetaEditor (press F4 in MetaTrader), then look in the Navigator window (left side) under the Include folder.</li><li>Key Files:<ul><li>Trade Functions: Look in Include/Trade/Trade.mqh to see how the terminal handles order execution.</li><li>Indicators: Look in Include/Indicators/ to see the source code for standard indicator classes.</li></ul></li><li>Shortcut: In your own code, you can right-click any #include filename or a standard library class (like CTrade) and select "Go to Definition" to jump directly to its source code.&nbsp;</li></ul><p><strong>2. Built-in "Kernel" Functions (Not Viewable)</strong></p><p>Functions like CopyBuffer(), iMA(), or OrderSend() are part of the MetaTrader executable core (.exe or .dll).&nbsp;</p><ul><li>The Reality: These are compiled "black boxes." You cannot see the raw C++ or machine code behind them within MetaEditor.</li><li>The Alternative: The best way to understand how they work is to consult the official MQL5 Reference Documentation, which provides the technical logic and parameters for every built-in function.&nbsp;</li></ul><p><strong>3. Working with External DLLs</strong></p><ul><li>If you are using custom functions from a DLL (Data Link Library), the code is also hidden unless you have the original C++ or C# source project.&nbsp;</li><li>To use them, you must declare their "header" in your MQL code using the #import command.&nbsp;</li></ul><p><br></p><p>Pro Tip: If you want to see how a specific indicator (like the RSI or MACD) is calculated, don't look for the built-in function; instead, look in the MQL5/Indicators/Examples folder, where the source code for standard indicators is provided as a learning resource.</p><p><br></p>