diff --git a/Documentation/UserManual/ProgrammingGuide.pdf b/Documentation/UserManual/ProgrammingGuide.pdf
index 7ccece1..46b2e6d 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 79b7599..1654b32 100644
--- a/Documentation/UserManual/ProgrammingGuide.tex
+++ b/Documentation/UserManual/ProgrammingGuide.tex
@@ -501,22 +501,44 @@ $$ S_{11}...S_{1n},S_{21}...S_{2n},...,S_{n1}...S_{nn} $$
 \event{Sets the storage type of a trace}{VNA:TRACe:TYPE}{<trace>, either by name or by index\\<type>, options are OVERWRITE, MAXHOLD or MINHOLD}
 \query{Queries the storage type of a trace}{VNA:TRACe:TYPE?}{<trace>, either by name or by index}{OVERWRITE, MAXHOLD or MINHOLD}
 
-\subsubsection{VNA:CALibration:TYPE}
-\event{Sets the calibration type. This command fails if the required measurements have not been taken yet}{VNA:CALibration:TYPE}{<type>, options are NONE, PORT\_1, PORT\_2, SOLT, NORMALIZE or TRL}
-\query{Queries the currently active calibration type}{VNA:CALibration:TYPE?}{None}{NONE, PORT\_1, PORT\_2, SOLT, NORMALIZE or TRL}
+\subsubsection{VNA:CALibration:ACTivate}
+\event{Activates a specific calibration. This command fails if the required measurements have not been taken yet}{VNA:CALibration:ACTivate}{<type>}
+\query{Queries the currently available calibration types}{VNA:CALibration:ACTivate?}{None}{comma-separated list of available calibration types}
 
-\subsubsection{VNA:CALibration:MEASure}
-\event{Starts a calibration measurement. This command fails if no device is connected, the VNA mode is not active or a calibration measurement is already in progress.}{VNA:CALibration:MEASure}{<type>, options are:\\
-\hspace{1cm}PORT\_1\_OPEN\\
-\hspace{1cm}PORT\_1\_SHORT\\
-\hspace{1cm}PORT\_1\_LOAD\\
-\hspace{1cm}PORT\_2\_OPEN\\
-\hspace{1cm}PORT\_2\_SHORT\\
-\hspace{1cm}PORT\_2\_LOAD\\
+\subsubsection{VNA:CALibration:NUMber}
+\query{Queries the number of available calibration measurements}{VNA:CALibration:NUMber?}{None}{<number of configured measurements>}
+
+\subsubsection{VNA:CALibration:RESET}
+\event{Resets the calibration. Deactivates the calibration and deletes all measurements.}{VNA:CALibration:RESET}{None}
+
+\subsubsection{VNA:CALibration:ADD}
+\event{Adds a new empty calibration measurement.}{VNA:CALibration:ADD}{<type> Measurement type, one of:\\
+\hspace{1cm}OPEN\\
+\hspace{1cm}SHORT\\
+\hspace{1cm}LOAD\\
 \hspace{1cm}THROUGH\\
 \hspace{1cm}ISOLATION\\
-\hspace{1cm}LINE\\
-}
+{[<standard>]}, calibration kit standard name, optional\\}
+
+\subsubsection{VNA:CALibration:TYPE}
+\query{Returns the type of the specified measurement}{VNA:CALibration:TYPE?}{<measurement number>}{Measurement type, one of:\\
+\hspace{1cm}OPEN\\
+\hspace{1cm}SHORT\\
+\hspace{1cm}LOAD\\
+\hspace{1cm}THROUGH\\
+\hspace{1cm}ISOLATION\\}
+
+\subsubsection{VNA:CALibration:PORT}
+\event{Sets the port for the specified measurement}{VNA:CALibration:PORT}{<measurement number> <port number>}
+\query{Returns the port for the specified measurement}{VNA:CALibration:PORT?}{<measurement number>}{<port number>}
+
+\subsubsection{VNA:CALibration:STANDARD}
+\event{Sets the calibration standard which will be used for the specified measurement}{VNA:CALibration:STANDARD}{<measurement number> <standard name>}
+\query{Returns the standard name for the specified measurement}{VNA:CALibration:STANDARD?}{<measurement number>}{Name of used calibration standard (from calibration kit)}
+
+\subsubsection{VNA:CALibration:MEASure}
+\event{Starts a calibration measurement. This command fails if no device is connected, the VNA mode is not active or a calibration measurement is already in progress.}{VNA:CALibration:MEASure}{<measurement 1>,<measurement 2>,...}
+Any number of measurements can be specified (by their number). These measurements will be taken simultaneously. This only works if they are measuring different ports (e.g. measure SHORT on port 1 and OPEN on port 2). If colliding measurements are specified (e.g. SHORT on port 1 and LOAD on port 1), an error is returned and no measurements are started.
 
 \subsubsection{VNA:CALibration:BUSY}
 \query{Queries whether a calibration measurement is ongoing}{VNA:CALibration:BUSY?}{None}{TRUE or FALSE}
diff --git a/Software/PC_Application/Calibration/calibration.cpp b/Software/PC_Application/Calibration/calibration.cpp
index b7bf04d..0bca1b2 100644
--- a/Software/PC_Application/Calibration/calibration.cpp
+++ b/Software/PC_Application/Calibration/calibration.cpp
@@ -36,8 +36,258 @@ bool operator==(const Calibration::CalType &lhs, const Calibration::CalType &rhs
 }
 
 Calibration::Calibration()
+    : SCPINode("CALibration")
 {
     caltype.type = Type::None;
+    unsavedChanges = false;
+
+    // create SCPI commands
+    add(new SCPICommand("ACTivate", [=](QStringList params) -> QString {
+        if(params.size() != 1) {
+            return SCPI::getResultName(SCPI::Result::Error);
+        } else {
+            auto availableCals = getAvailableCalibrations();
+            for(auto caltype : availableCals) {
+                if(caltype.getShortString().compare(params[0], Qt::CaseInsensitive) == 0) {
+                    // found a match
+                    // check if calibration can be activated
+                    if(canCompute(caltype)) {
+                        compute(caltype);
+                    } else {
+                        return SCPI::getResultName(SCPI::Result::Error);
+                    }
+                }
+            }
+            // if we get here, the supplied parameter did not match any of the available calibrations
+            return SCPI::getResultName(SCPI::Result::Error);
+        }
+        return SCPI::getResultName(SCPI::Result::Empty);
+    }, [=](QStringList) -> QString {
+        auto availableCals = getAvailableCalibrations();
+        if(availableCals.size() == 0) {
+            return SCPI::getResultName(SCPI::Result::Empty);
+        }
+        auto ret = availableCals[0].getShortString();
+        for(unsigned int i=1;i<availableCals.size();i++) {
+            ret += ",";
+            ret += availableCals[i].getShortString();
+        }
+        return ret;
+    }));
+    add(new SCPICommand("NUMber", nullptr, [=](QStringList) -> QString {
+        return QString::number(measurements.size());
+    }));
+    add(new SCPICommand("RESET", [=](QStringList) -> QString {
+        reset();
+        return SCPI::getResultName(SCPI::Result::Empty);
+    }, nullptr));
+    add(new SCPICommand("ADD", [=](QStringList params) -> QString {
+        if(params.size() < 1) {
+            // no measurement type specified
+            return SCPI::getResultName(SCPI::Result::Error);
+        } else {
+            // parse measurement type
+            auto type = CalibrationMeasurement::Base::TypeFromString(params[0]);
+            auto newMeas = newMeasurement(type);
+            if(!newMeas) {
+                // failed to create this type of measurement
+                return SCPI::getResultName(SCPI::Result::Error);
+            }
+            if(params.size() == 2) {
+                // standard name given
+                CalStandard::Virtual *standard = nullptr;
+                for(auto s : newMeas->supportedStandards()) {
+                    if(s->getName().compare(params[1], Qt::CaseInsensitive) == 0) {
+                        // use this standard
+                        standard = s;
+                    }
+                }
+                if(!standard) {
+                    // specified standard not available
+                    return SCPI::getResultName(SCPI::Result::Error);
+                }
+                newMeas->setStandard(standard);
+            }
+            measurements.push_back(newMeas);
+            return SCPI::getResultName(SCPI::Result::Empty);
+        }
+    }, nullptr));
+    add(new SCPICommand("TYPE", nullptr, [=](QStringList params) -> QString {
+        if(params.size() < 1) {
+            // no measurement number specified
+            return SCPI::getResultName(SCPI::Result::Error);
+        } else {
+            bool okay;
+            unsigned int number = params[0].toUInt(&okay);
+            if(!okay || number >= measurements.size()) {
+                // invalid measurement specified
+                return SCPI::getResultName(SCPI::Result::Error);
+            }
+            return CalibrationMeasurement::Base::TypeToString(measurements[number]->getType());
+        }
+    }));
+    add(new SCPICommand("PORT", [=](QStringList params) -> QString {
+        if(params.size() < 1) {
+            // invalid number of parameters
+            return SCPI::getResultName(SCPI::Result::Error);
+        } else {
+            bool okay;
+            unsigned int number = params[0].toUInt(&okay);
+            if(!okay || number >= measurements.size()) {
+                // invalid measurement specified
+                return SCPI::getResultName(SCPI::Result::Error);
+            }
+            auto meas = measurements[number];
+            auto onePort = dynamic_cast<CalibrationMeasurement::OnePort*>(meas);
+            if(onePort) {
+                if(params.size() != 2) {
+                    // invalid number of parameters
+                    return SCPI::getResultName(SCPI::Result::Error);
+                }
+                bool okay;
+                int number = params[1].toInt(&okay);
+                if(!okay || number < 1 || number > VirtualDevice::getInfo(VirtualDevice::getConnected()).ports) {
+                    // invalid port specified
+                    return SCPI::getResultName(SCPI::Result::Error);
+                }
+                onePort->setPort(number);
+                return SCPI::getResultName(SCPI::Result::Empty);
+            }
+            auto twoPort = dynamic_cast<CalibrationMeasurement::TwoPort*>(meas);
+            if(twoPort) {
+                if(params.size() != 3) {
+                    // invalid number of parameters
+                    return SCPI::getResultName(SCPI::Result::Error);
+                }
+                bool okay1;
+                int port1 = params[1].toInt(&okay1);
+                bool okay2;
+                int port2 = params[2].toInt(&okay2);
+                if(!okay1 || !okay2 || port1 < 1 || port2 > VirtualDevice::getInfo(VirtualDevice::getConnected()).ports
+                         || port2 < 1 || port2 > VirtualDevice::getInfo(VirtualDevice::getConnected()).ports) {
+                    // invalid port specified
+                    return SCPI::getResultName(SCPI::Result::Error);
+                }
+                twoPort->setPort1(port1);
+                twoPort->setPort2(port2);
+                return SCPI::getResultName(SCPI::Result::Empty);
+            }
+            return SCPI::getResultName(SCPI::Result::Error);
+        }
+    }, [=](QStringList params) -> QString {
+        if(params.size() != 1) {
+            // invalid number of parameters
+            return SCPI::getResultName(SCPI::Result::Error);
+        } else {
+            bool okay;
+            unsigned int number = params[0].toUInt(&okay);
+            if(!okay || number >= measurements.size()) {
+                // invalid measurement specified
+                return SCPI::getResultName(SCPI::Result::Error);
+            }
+            auto meas = measurements[number];
+            auto onePort = dynamic_cast<CalibrationMeasurement::OnePort*>(meas);
+            if(onePort) {
+                return QString::number(onePort->getPort());
+            }
+            auto twoPort = dynamic_cast<CalibrationMeasurement::TwoPort*>(meas);
+            if(twoPort) {
+                return QString::number(twoPort->getPort1()) + " " + QString::number(twoPort->getPort2());
+            }
+            return SCPI::getResultName(SCPI::Result::Error);
+        }
+    }));
+    add(new SCPICommand("STANDARD", [=](QStringList params) -> QString {
+        if(params.size() != 2) {
+            // invalid number of parameters
+            return SCPI::getResultName(SCPI::Result::Error);
+        } else {
+            bool okay;
+            unsigned int number = params[0].toUInt(&okay);
+            if(!okay || number >= measurements.size()) {
+                // invalid measurement specified
+                return SCPI::getResultName(SCPI::Result::Error);
+            }
+            auto meas = measurements[number];
+            for(auto s : meas->supportedStandards()) {
+                if(s->getName().compare(params[1], Qt::CaseInsensitive) == 0) {
+                    // use this standard
+                    meas->setStandard(s);
+                    return SCPI::getResultName(SCPI::Result::Empty);
+                }
+            }
+            // specified standard not available
+            return SCPI::getResultName(SCPI::Result::Error);
+        }
+    }, [=](QStringList params) -> QString {
+        if(params.size() != 1) {
+            // invalid number of parameters
+            return SCPI::getResultName(SCPI::Result::Error);
+        } else {
+            bool okay;
+            unsigned int number = params[0].toUInt(&okay);
+            if(!okay || number >= measurements.size()) {
+                // invalid measurement specified
+                return SCPI::getResultName(SCPI::Result::Error);
+            }
+            auto s = measurements[number]->getStandard();
+            if(s) {
+                s->getName();
+            } else {
+                // no standard set
+                return "None";
+            }
+        }
+    }));
+    add(new SCPICommand("MEASure", [=](QStringList params) -> QString {
+        if(params.size() < 1 ) {
+            // no measurement specified
+            // TODO check if measurement is already running
+            return SCPI::getResultName(SCPI::Result::Error);
+        } else {
+            // assemble list of measurements to take
+            std::set<CalibrationMeasurement::Base*> m;
+            for(QString p : params) {
+                bool okay = false;
+                unsigned int number = p.toUInt(&okay);
+                if(!okay || number >= measurements.size()) {
+                    // invalid measurement specified
+                    return SCPI::getResultName(SCPI::Result::Error);
+                } else {
+                    m.insert(measurements[number]);
+                }
+            }
+            if(CalibrationMeasurement::Base::canMeasureSimultaneously(m)) {
+                emit startMeasurements(m);
+                return SCPI::getResultName(SCPI::Result::Empty);
+            } else {
+                // can't start these measurements simultaneously
+                return SCPI::getResultName(SCPI::Result::Error);
+            }
+        }
+    }, nullptr));
+    add(new SCPICommand("SAVE", [=](QStringList params) -> QString {
+        if(params.size() != 1 || getCaltype().type == Calibration::Type::None) {
+            // no filename given or no calibration active
+            return SCPI::getResultName(SCPI::Result::Error);
+        }
+        if(!toFile(params[0])) {
+            // some error when writing the calibration file
+            return SCPI::getResultName(SCPI::Result::Error);
+        }
+        return SCPI::getResultName(SCPI::Result::Empty);
+    }, nullptr));
+    add(new SCPICommand("LOAD", nullptr, [=](QStringList params) -> QString {
+        if(params.size() != 1) {
+            // no filename given or no calibration active
+            return SCPI::getResultName(SCPI::Result::False);
+        }
+        if(!fromFile(params[0])) {
+            // some error when loading the calibration file
+            return SCPI::getResultName(SCPI::Result::False);
+        }
+        return SCPI::getResultName(SCPI::Result::True);
+    }));
 }
 
 QString Calibration::TypeToString(Calibration::Type type)
@@ -284,7 +534,7 @@ void Calibration::edit()
                 ui->createDefault->blockSignals(false);
                 return;
             }
-            measurements.clear();
+            deleteMeasurements();
         }
         createDefaultMeasurements((DefaultMeasurements) (ui->createDefault->currentIndex() - 1));
         updateMeasurementTable();
@@ -845,6 +1095,7 @@ bool Calibration::toFile(QString filename)
     kit.toFile(calkit_file);
     this->currentCalFile = calibration_file;    // if all ok, remember this
 
+    unsavedChanges = false;
     return true;
 }
 
@@ -888,6 +1139,7 @@ bool Calibration::fromFile(QString filename)
         return false;
     }
 
+    unsavedChanges = false;
     return true;
 }
 
@@ -1012,10 +1264,7 @@ bool Calibration::compute(Calibration::CalType type)
 
 void Calibration::reset()
 {
-    for(auto m : measurements) {
-        delete m;
-    }
-    measurements.clear();
+    deleteMeasurements();
     deactivate();
 }
 
@@ -1033,6 +1282,7 @@ void Calibration::addMeasurements(std::set<CalibrationMeasurement::Base *> m, co
     for(auto meas : m) {
         meas->addPoint(data);
     }
+    unsavedChanges = true;
 }
 
 void Calibration::clearMeasurements(std::set<CalibrationMeasurement::Base *> m)
@@ -1116,6 +1366,14 @@ void Calibration::createDefaultMeasurements(Calibration::DefaultMeasurements dm)
     }
 }
 
+void Calibration::deleteMeasurements()
+{
+    for(auto m : measurements) {
+        delete m;
+    }
+    measurements.clear();
+}
+
 bool Calibration::hasFrequencyOverlap(std::vector<CalibrationMeasurement::Base *> m, double *startFreq, double *stopFreq, int *points)
 {
     double minResolution = std::numeric_limits<double>::max();
diff --git a/Software/PC_Application/Calibration/calibration.h b/Software/PC_Application/Calibration/calibration.h
index 6bdb940..f6d8c25 100644
--- a/Software/PC_Application/Calibration/calibration.h
+++ b/Software/PC_Application/Calibration/calibration.h
@@ -5,8 +5,9 @@
 #include "calibrationmeasurement.h"
 #include "calkit.h"
 #include "Traces/trace.h"
+#include "scpi.h"
 
-class Calibration : public QObject, public Savable
+class Calibration : public QObject, public Savable, public SCPINode
 {
     Q_OBJECT
 
@@ -115,6 +116,7 @@ private:
     };
     static QString DefaultMeasurementsToString(DefaultMeasurements dm);
     void createDefaultMeasurements(DefaultMeasurements dm);
+    void deleteMeasurements();
 
     bool hasFrequencyOverlap(std::vector<CalibrationMeasurement::Base*> m, double *startFreq = nullptr, double *stopFreq = nullptr, int *points = nullptr);
     CalibrationMeasurement::Base* findMeasurement(CalibrationMeasurement::Base::Type type, int port1 = 0, int port2 = 0);
@@ -145,6 +147,8 @@ private:
 
     QString descriptiveCalName();
     QString currentCalFile;
+
+    bool unsavedChanges;
 };
 
 #endif // CALIBRATION2_H
diff --git a/Software/PC_Application/Calibration/calibrationmeasurement.cpp b/Software/PC_Application/Calibration/calibrationmeasurement.cpp
index 2e10ce3..35d616c 100644
--- a/Software/PC_Application/Calibration/calibrationmeasurement.cpp
+++ b/Software/PC_Application/Calibration/calibrationmeasurement.cpp
@@ -95,7 +95,7 @@ QString CalibrationMeasurement::Base::TypeToString(CalibrationMeasurement::Base:
 CalibrationMeasurement::Base::Type CalibrationMeasurement::Base::TypeFromString(QString s)
 {
     for(int i=0;i<(int) Type::Last;i++) {
-        if(TypeToString((Type) i) == s) {
+        if(TypeToString((Type) i).compare(s, Qt::CaseInsensitive) == 0) {
             return (Type) i;
         }
     }
@@ -188,6 +188,11 @@ QDateTime CalibrationMeasurement::Base::getTimestamp() const
     return timestamp;
 }
 
+CalStandard::Virtual* CalibrationMeasurement::Base::getStandard() const
+{
+    return standard;
+}
+
 double CalibrationMeasurement::OnePort::minFreq()
 {
     if(points.size() > 0) {
diff --git a/Software/PC_Application/Calibration/calibrationmeasurement.h b/Software/PC_Application/Calibration/calibrationmeasurement.h
index d407cc8..985417c 100644
--- a/Software/PC_Application/Calibration/calibrationmeasurement.h
+++ b/Software/PC_Application/Calibration/calibrationmeasurement.h
@@ -54,6 +54,8 @@ public:
     static bool canMeasureSimultaneously(std::set<Base *> measurements);
     QDateTime getTimestamp() const;
 
+    CalStandard::Virtual *getStandard() const;
+
 protected:
 signals:
     void standardChanged(CalStandard::Virtual* newStandard);
@@ -101,7 +103,7 @@ protected:
 signals:
     void portChanged(int p);
 protected:
-    int port;
+    int port; // starts at 1
     std::vector<Point> points;
 };
 
@@ -182,7 +184,7 @@ signals:
     void port2Changed(int p);
     void reverseStandardChanged(bool r);
 protected:
-    int port1, port2;
+    int port1, port2; // starts at 1
     bool reverseStandard; // Set to true if standard is defined with ports swapped
     std::vector<Point> points;
 };
diff --git a/Software/PC_Application/VNA/vna.cpp b/Software/PC_Application/VNA/vna.cpp
index 189eb7d..6836e8d 100644
--- a/Software/PC_Application/VNA/vna.cpp
+++ b/Software/PC_Application/VNA/vna.cpp
@@ -1403,77 +1403,10 @@ void VNA::SetupSCPI()
         return QString::number(settings.Power.frequency, 'f', 0);
     }));
     SCPINode::add(traceWidget);
-    auto scpi_cal = new SCPINode("CALibration");
-    SCPINode::add(scpi_cal);
-    scpi_cal->add(new SCPICommand("TYPE", [=](QStringList params) -> QString {
-        if(params.size() != 1) {
-            return SCPI::getResultName(SCPI::Result::Error);
-        } else {
-            auto availableCals = cal.getAvailableCalibrations();
-            for(auto caltype : availableCals) {
-                if(caltype.getShortString().compare(params[0], Qt::CaseInsensitive) == 0) {
-                    // found a match
-                    // check if calibration can be activated
-                    if(cal.canCompute(caltype)) {
-                        ApplyCalibration(caltype);
-                    } else {
-                        return SCPI::getResultName(SCPI::Result::Error);
-                    }
-                }
-            }
-            // if we get here, the supplied parameter did not match any of the available calibrations
-            return SCPI::getResultName(SCPI::Result::Error);
-        }
-        return SCPI::getResultName(SCPI::Result::Empty);
-    }, [=](QStringList) -> QString {
-        auto ret = cal.getCaltype().getShortString();
-        return ret;
-    }));
-    scpi_cal->add(new SCPICommand("MEASure", [=](QStringList params) -> QString {
-        if(params.size() != 1 || CalibrationMeasurementActive() || !window->getDevice() || isActive != true) {
-            // no measurement specified, still busy or invalid mode
-            return SCPI::getResultName(SCPI::Result::Error);
-        } else {
-            // TODO
-//            auto meas = Calibration::MeasurementFromString(params[0].replace('_', ' '));
-//            if(meas == Calibration::Measurement::Last) {
-//                // failed to parse string
-//                return SCPI::getResultName(SCPI::Result::Error);
-//            } else {
-//                std::set<Calibration::Measurement> m;
-//                m.insert(meas);
-////                StartCalibrationMeasurements(m);
-//            }
-        }
-        return SCPI::getResultName(SCPI::Result::Empty);
-    }, nullptr));
-    scpi_cal->add(new SCPICommand("BUSy", nullptr, [=](QStringList) -> QString {
+    SCPINode::add(&cal);
+    cal.add(new SCPICommand("BUSy", nullptr, [=](QStringList) -> QString {
         return CalibrationMeasurementActive() ? SCPI::getResultName(SCPI::Result::True) : SCPI::getResultName(SCPI::Result::False);
     }));
-    scpi_cal->add(new SCPICommand("SAVE", [=](QStringList params) -> QString {
-        if(params.size() != 1 || cal.getCaltype().type == Calibration::Type::None) {
-            // no filename given or no calibration active
-            return SCPI::getResultName(SCPI::Result::Error);
-        }
-        if(!cal.toFile(params[0])) {
-            // some error when writing the calibration file
-            return SCPI::getResultName(SCPI::Result::Error);
-        }
-        calEdited = false;
-        return SCPI::getResultName(SCPI::Result::Empty);
-    }, nullptr));
-    scpi_cal->add(new SCPICommand("LOAD", nullptr, [=](QStringList params) -> QString {
-        if(params.size() != 1) {
-            // no filename given or no calibration active
-            return SCPI::getResultName(SCPI::Result::False);
-        }
-        if(!cal.fromFile(params[0])) {
-            // some error when loading the calibration file
-            return SCPI::getResultName(SCPI::Result::False);
-        }
-        calEdited = false;
-        return SCPI::getResultName(SCPI::Result::True);
-    }));
 }
 
 void VNA::ConstrainAndUpdateFrequencies()