diff --git a/Documentation/UserManual/ProgrammingGuide.pdf b/Documentation/UserManual/ProgrammingGuide.pdf
index 7eff4fb..f7e7546 100644
Binary files a/Documentation/UserManual/ProgrammingGuide.pdf and b/Documentation/UserManual/ProgrammingGuide.pdf differ
diff --git a/Documentation/UserManual/ProgrammingGuide.tex b/Documentation/UserManual/ProgrammingGuide.tex
index a3d502a..ded2d15 100644
--- a/Documentation/UserManual/ProgrammingGuide.tex
+++ b/Documentation/UserManual/ProgrammingGuide.tex
@@ -212,7 +212,9 @@ Some commands are both events and queries, depending on whether the question mar
 \section{Commands}
 \subsection{General Commands}
 \subsubsection{*IDN}
-\query{Returns the identifications string}{*IDN?}{None}{LibreVNA-GUI}
+\query{Returns the identifications string}{*IDN?}{None}{LibreVNA,LibreVNA-GUI,dummy\_serial,<software version>}
+\subsubsection{*OPC}
+\query{Returns a 1 after every previous command has been handled}{*OPC?}{None}{1}
 \subsubsection{*LST}
 \query{Lists all available commands}{*LST?}{None}{List of commands, separated by newline}
 \subsection{Device Commands}
diff --git a/Software/PC_Application/LibreVNA-GUI/appwindow.cpp b/Software/PC_Application/LibreVNA-GUI/appwindow.cpp
index fc27de9..946b722 100644
--- a/Software/PC_Application/LibreVNA-GUI/appwindow.cpp
+++ b/Software/PC_Application/LibreVNA-GUI/appwindow.cpp
@@ -477,7 +477,10 @@ void AppWindow::CreateToolbars()
 void AppWindow::SetupSCPI()
 {
     scpi.add(new SCPICommand("*IDN", nullptr, [=](QStringList){
-        return "LibreVNA-GUI";
+        return "LibreVNA,LibreVNA-GUI,dummy_serial,"+appVersion;
+    }));
+    scpi.add(new SCPICommand("*OPC", nullptr, [=](QStringList){
+        return "1";
     }));
     auto scpi_dev = new SCPINode("DEVice");
     scpi.add(scpi_dev);