diff --git a/src/musredit_qt5/mupp/CMakeLists.txt b/src/musredit_qt5/mupp/CMakeLists.txt
index ba38114f..34868248 100644
--- a/src/musredit_qt5/mupp/CMakeLists.txt
+++ b/src/musredit_qt5/mupp/CMakeLists.txt
@@ -48,7 +48,8 @@ set(MUPP_SOURCE_FILES
   Pmupp.cpp
   PmuppScript.cpp 
   PmuppGui.cpp
-  PGetNormValDialog.cpp
+  PVarDialog.cpp
+#as35  PGetNormValDialog.cpp
 )
 
 if (APPLE)
diff --git a/src/musredit_qt5/mupp/PGetNormValDialog.h b/src/musredit_qt5/mupp/PGetNormValDialog.h
deleted file mode 100644
index 0f8e99c1..00000000
--- a/src/musredit_qt5/mupp/PGetNormValDialog.h
+++ /dev/null
@@ -1,54 +0,0 @@
-/***************************************************************************
-
-  PGetNormValDialog.h
-
-  Author: Andreas Suter
-  e-mail: andreas.suter@psi.ch
-
-***************************************************************************/
-
-/***************************************************************************
- *   Copyright (C) 2007-2020 by Andreas Suter                              *
- *   andreas.suter@psi.ch                                                  *
- *                                                                         *
- *   This program 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 2 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, write to the                         *
- *   Free Software Foundation, Inc.,                                       *
- *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
- ***************************************************************************/
-
-#ifndef _PGETNORMVALDIALOG_H_
-#define _PGETNORMVALDIALOG_H_
-
-#include <QDialog>
-#include <QLineEdit>
-
-class PGetNormValDialog : public QDialog
-{
-  Q_OBJECT
-
-  public:
-    PGetNormValDialog(double dval, QWidget *parent = 0, Qt::WindowFlags f = 0);
-    virtual ~PGetNormValDialog() {}
-
-    virtual double getValue() { return fValue; }
-
-  private:
-    double fValue;
-    QLineEdit *fEdit;
-
-  private slots:
-    virtual void gotValue(const QString& str);
-};
-
-#endif // _PGETNORMVALDIALOG_H_
diff --git a/src/musredit_qt5/mupp/PVarDialog.cpp b/src/musredit_qt5/mupp/PVarDialog.cpp
new file mode 100644
index 00000000..f390a4dc
--- /dev/null
+++ b/src/musredit_qt5/mupp/PVarDialog.cpp
@@ -0,0 +1,404 @@
+/***************************************************************************
+
+  PVarDialog.cpp
+
+  Author: Andreas Suter
+  e-mail: andreas.suter@psi.ch
+
+***************************************************************************/
+
+/***************************************************************************
+ *   Copyright (C) 2007-2020 by Andreas Suter                              *
+ *   andreas.suter@psi.ch                                                  *
+ *                                                                         *
+ *   This program 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 2 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, write to the                         *
+ *   Free Software Foundation, Inc.,                                       *
+ *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
+ ***************************************************************************/
+
+#include <iostream>
+
+#include <QVBoxLayout>
+#include <QHBoxLayout>
+#include <QSplitter>
+#include <QListWidgetItem>
+#include <QMessageBox>
+#include <QLabel>
+#include <QRegularExpression>
+
+#include "PVarDialog.h"
+
+//--------------------------------------------------------------------------
+PShowVarNameDialog::PShowVarNameDialog(PCollInfo &info)
+{
+  // if fCollName is a path name, extract the fln
+  QString collNameStr(info.fCollName);
+  if (collNameStr.contains("/")) {
+    QStringList tok = collNameStr.split('/', QString::SkipEmptyParts);
+    collNameStr = tok[tok.count()-1];
+  }
+  QLabel *collName = new QLabel(collNameStr);
+  QLabel *numVars = new QLabel(QString("#variables: %1").arg(info.fVarName.count()));
+  QListWidget *list = new QListWidget();
+  for (int i=0; i<info.fVarName.count(); i++) {
+    QListWidgetItem *newItem = new QListWidgetItem;
+    newItem->setText(QString("%1 : %2").arg(i, 2).arg(info.fVarName[i]));
+    list->addItem(newItem);
+  }
+  QPushButton *done = new QPushButton("Done", this);
+
+  QVBoxLayout *vLayout = new QVBoxLayout;
+  vLayout->addWidget(collName);
+  vLayout->addWidget(numVars);
+  vLayout->addWidget(list);
+  vLayout->addWidget(done);
+
+  connect(done, SIGNAL( clicked() ), this, SLOT( accept() ));
+
+  resize(300, 450);
+  setLayout(vLayout);
+  setModal(false);
+  setWindowTitle("Variable Names");
+
+  QString iconName("");
+  if (true) // <-- NEEDS TO BE PROPERLY IMPLEMENTED
+    iconName = QString(":/icons/varEdit-dark.svg");
+  else
+    iconName = QString(":/icons/varEdit-plain.svg");
+  setWindowIcon( QIcon( QPixmap(iconName) ) );
+}
+
+//--------------------------------------------------------------------------
+PVarDialog::PVarDialog(QVector<PCollInfo> collection_list, bool darkTheme,
+                       QWidget *parent, Qt::WindowFlags f) :
+  QDialog(parent, f), fCollList(collection_list)
+{
+  fVarEdit = new QPlainTextEdit();
+  fCollectionView = new QListWidget();
+  fCancel = new QPushButton("&Cancel", this);
+  fCheck = new QPushButton("Chec&k", this);
+  fAdd = new QPushButton("&Add", this);
+  fHelp = new QPushButton("&Help", this);
+  fShowVarName = new QPushButton("Show&VarName", this);
+
+  // fill collection view
+  for (int i=0; i<fCollList.count(); i++) {
+    QListWidgetItem *newItem = new QListWidgetItem;
+    newItem->setText(fCollList[i].fCollName);
+    fCollectionView->addItem(newItem);
+  }
+  fCollectionView->setSelectionMode(QAbstractItemView::ExtendedSelection);
+
+  QHBoxLayout *hLayout0 = new QHBoxLayout;
+  hLayout0->addWidget(fShowVarName);
+  hLayout0->addWidget(fHelp);
+
+  QHBoxLayout *hLayout1 = new QHBoxLayout;
+  hLayout1->addWidget(fCancel);
+  hLayout1->addWidget(fCheck);
+  hLayout1->addWidget(fAdd);
+
+  QLabel *varLabel = new QLabel("Edit Variables:");
+  QVBoxLayout *varVLayout = new QVBoxLayout;
+  varVLayout->addWidget(varLabel);
+  varVLayout->addWidget(fVarEdit);
+
+  QLabel *collLabel = new QLabel("Collections:");
+  QVBoxLayout *collVLayout = new QVBoxLayout;
+  collVLayout->addWidget(collLabel);
+  collVLayout->addWidget(fCollectionView);
+
+  QWidget *varWidget = new QWidget(this); // only needed since splitter needs a QWidget
+  varWidget->setLayout(varVLayout);
+  QWidget *collWidget = new QWidget(this); // only needed since splitter needs a QWidget
+  collWidget->setLayout(collVLayout);
+
+  QSplitter *splitter = new QSplitter(Qt::Vertical, this);
+  splitter->addWidget(varWidget);
+  splitter->addWidget(collWidget);
+
+  QVBoxLayout *vLayout = new QVBoxLayout;
+  vLayout->addWidget(splitter);
+  vLayout->addLayout(hLayout0);
+  vLayout->addLayout(hLayout1);
+
+  fVarEdit->resize(600, 300);
+  setLayout(vLayout);
+  resize(600, 450);
+
+  connect(fCancel, SIGNAL( clicked() ), this, SLOT( reject() ));
+  connect(fCheck, SIGNAL( clicked() ), this, SLOT( check() ));
+  connect(fAdd, SIGNAL( clicked() ), this, SLOT( add() ));
+  connect(fHelp, SIGNAL( clicked() ), this, SLOT( help() ));
+  connect(fShowVarName, SIGNAL( clicked() ), this, SLOT( showVarNames() ));
+
+  QString iconName("");
+  if (darkTheme)
+    iconName = QString(":/icons/varEdit-dark.svg");
+  else
+    iconName = QString(":/icons/varEdit-plain.svg");
+  setWindowIcon( QIcon( QPixmap(iconName) ) );
+}
+
+//--------------------------------------------------------------------------
+void PVarDialog::check()
+{
+  if (!basic_check())
+    return;
+
+  if (!var_consistency_check())
+    return;
+
+  // create the collection index vector
+  QVector<int> idx;
+  QList<QListWidgetItem *> selected = fCollectionView->selectedItems();
+  for (int i=0; i<selected.count(); i++) {
+    idx.push_back(fCollectionView->row(selected[i]));
+  }
+  emit check_request(fVarEdit->toPlainText(), idx);
+}
+
+//--------------------------------------------------------------------------
+void PVarDialog::add()
+{
+  if (fVarEdit->toPlainText().isEmpty()) {
+    QMessageBox::critical(this, "**ERROR**", "No input available.");
+    return;
+  }
+  if (fCollectionView->selectedItems().count() == 0) {
+    QMessageBox::critical(this, "**ERROR**", "One or more collection(s) need to linked to the variable(s).");
+    return;
+  }
+
+  if (!basic_check())
+    return;
+
+  if (!var_consistency_check())
+    return;
+
+  // create the collection index vector
+  QVector<int> idx;
+  QList<QListWidgetItem *> selected = fCollectionView->selectedItems();
+  for (int i=0; i<selected.count(); i++) {
+    idx.push_back(fCollectionView->row(selected[i]));
+  }
+
+  emit check_request(fVarEdit->toPlainText(), idx);
+}
+
+//--------------------------------------------------------------------------
+void PVarDialog::help()
+{
+  QMessageBox::information(this, "Var Help", "Syntax: var <var_name> = <expr>.\n<expr> can contain identifiers defined in the collections.\nExample:\nvar sigSC = pow(abs(pow($sigma,2.0)-pow(0.11,2.0)),0.5)");
+}
+
+//--------------------------------------------------------------------------
+void PVarDialog::showVarNames()
+{
+  // get the selected collection
+  if (fCollectionView->selectedItems().count() == 0) {
+    QMessageBox::critical(this, "**ERROR**", "At least one collection needs to be selected.");
+    return;
+  }
+  if (fCollectionView->selectedItems().count() > 1) {
+    QMessageBox::critical(this, "**ERROR**", "Currently only the vars of a single collection can be shown.");
+    return;
+  }
+  int idx = fCollectionView->currentRow();
+
+  if (idx >= fCollList.count()) {
+    QMessageBox::critical(this, "**ERROR**", QString("Collection idx=%1 > #Collections=%2. This never should have happened.").arg(idx).arg(fCollList.count()));
+    return;
+  }
+
+  PCollInfo info = fCollList[idx];
+
+  PShowVarNameDialog *dialog = new PShowVarNameDialog(info);
+  dialog->show();
+}
+
+//--------------------------------------------------------------------------
+bool PVarDialog::basic_check()
+{
+  QString varStr = fVarEdit->toPlainText();
+  bool ok;
+
+  if (varStr.isEmpty()) {
+    QMessageBox::critical(this, "**ERROR**", "No input available.");
+    return false;
+  }
+  if (fCollectionView->selectedItems().count() == 0) {
+    QMessageBox::critical(this, "**ERROR**", "One or more collection(s) need to linked to the variable(s).");
+    return false;
+  }
+
+  // tokenize variable input
+  QStringList strList = varStr.split(QRegularExpression("\\s+"), QString::SkipEmptyParts);
+
+  // check if there are ANY var definitions
+  ok = false;
+  for (int i=0; i<strList.count(); i++) {
+    if (strList[i] == "var") {
+      ok = true;
+      break;
+    }
+  }
+  if (!ok) {
+    QMessageBox::critical(this, "**ERROR**", "<b>NO</b> 'var' definition found.");
+    return false;
+  }
+
+  // check that for each variable, there is also an Err variable present
+  QStringList varNames = collectVarNames(strList, ok);
+  if (!ok) {
+    QMessageBox::critical(this, "**ERROR**", "found 'var' without <var_name>.");
+    return false;
+  }
+  QString name("");
+  if (!hasErrorDef(varNames, name)) {
+    QMessageBox::critical(this, "**ERROR**", QString("found &lt;var_name&gt;=%1 without corresponding %1Err.<br>Both, a variable <b>and</b> its corresponding error variable needs to be defined.").arg(name));
+    return false;
+  }
+
+  return true;
+}
+
+//--------------------------------------------------------------------------
+bool PVarDialog::var_consistency_check()
+{
+  QString varStr = fVarEdit->toPlainText();
+
+  // collect all identifiers
+  int idx = 0, idxEnd = 0;
+  QStringList varNames;
+  QVector<int> isIdendifier;
+  char ch;
+  bool done;
+  do {
+    idx = varStr.indexOf("$", idx);
+    if (idx > -1) { // found identifier
+      idxEnd = idx+1;
+      done = false;
+      do {
+        ch = varStr[idxEnd].toLatin1();
+        if (isalnum(ch) || (ch == '_'))
+          idxEnd++;
+        else
+          done = true;
+      } while (!done && (idxEnd <= varStr.length()));
+      varNames << varStr.mid(idx+1, idxEnd-idx-1);
+      isIdendifier.push_back(1);
+      idx++;
+    }
+  } while (idx != -1);
+
+  // collect all the variable names
+  idx = 0;
+  do {
+    idx = varStr.indexOf("var ", idx);
+    if (idx > -1) { // found variable
+      idxEnd = varStr.indexOf("=", idx);
+      if (idxEnd == -1) {
+        return false;
+      }
+      varNames << varStr.mid(idx+4, idxEnd-idx-5);
+      isIdendifier.push_back(0);
+      idx++;
+    }
+  } while (idx != -1);
+
+  // make sure that identifier is found in collection if it is not a variable
+  bool isVar = false;
+  bool found = false;
+  QString str;
+  QList<QListWidgetItem *> selColl = fCollectionView->selectedItems();
+  for (int i=0; i<varNames.count(); i++) {
+    if (isIdendifier[i] == 0) // it is a variable, hence nothing to be done
+      continue;
+    str = varNames[i];
+    if (str.endsWith("Err")) {
+      str = str.left(str.indexOf("Err"));
+    }
+    isVar = false;
+    for (int j=i+1; j<varNames.count(); j++) {
+      if ((varNames[j] == str) && isIdendifier[j] == 0) {
+        isVar = true;
+        break;
+      }
+    }
+    if (isVar)
+      continue;
+
+    for (int j=0; j<selColl.count(); j++) {
+      idx = fCollectionView->row(selColl[j]);
+      found = false;
+      for (int k=0; k<fCollList[idx].fVarName.count(); k++) {
+        if (str == fCollList[idx].fVarName[k]) {
+          found = true;
+          break;
+        }
+      }
+      if (!found) {
+        QMessageBox::critical(this, "**ERROR**", QString("Identifier '%1' not present in selected collection '%2'").arg(str).arg(fCollList[idx].fCollName));
+        return false;
+      }
+    }
+  }
+
+  return true;
+}
+
+//--------------------------------------------------------------------------
+QStringList PVarDialog::collectVarNames(QStringList &list, bool &ok)
+{
+  QStringList name;
+
+  ok = true;
+  for (int i=0; i<list.count(); i++) {
+    if (list[i] == "var") {
+      if (i+1 >= list.count()) {
+        ok = false;
+      } else {
+        name << list[i+1];
+        i++;
+      }
+    }
+  }
+
+  return name;
+}
+
+//--------------------------------------------------------------------------
+bool PVarDialog::hasErrorDef(QStringList &varNames, QString &name)
+{
+  QString errStr;
+  for (int i=0; i<varNames.count(); i++) {
+    if (!varNames[i].contains("Err", Qt::CaseSensitive)) { // not an error variable
+      errStr = varNames[i] + "Err";
+      bool ok = false;
+      for (int j=0; j<varNames.count(); j++) {
+        if (varNames[j] == errStr) {
+          ok = true;
+          break;
+        }
+      }
+      if (!ok) {
+        name = varNames[i];
+        return ok;
+      }
+    }
+  }
+
+  return true;
+}
diff --git a/src/musredit_qt5/mupp/PGetNormValDialog.cpp b/src/musredit_qt5/mupp/PVarDialog.h
similarity index 59%
rename from src/musredit_qt5/mupp/PGetNormValDialog.cpp
rename to src/musredit_qt5/mupp/PVarDialog.h
index fad3a0d1..e18668a1 100644
--- a/src/musredit_qt5/mupp/PGetNormValDialog.cpp
+++ b/src/musredit_qt5/mupp/PVarDialog.h
@@ -1,6 +1,6 @@
 /***************************************************************************
 
-  PGetNormValDialog.cpp
+  PVarDialog.h
 
   Author: Andreas Suter
   e-mail: andreas.suter@psi.ch
@@ -27,49 +27,66 @@
  *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
  ***************************************************************************/
 
-#include <QVBoxLayout>
-#include <QHBoxLayout>
-#include <QLabel>
-#include <QLineEdit>
-#include <QDoubleValidator>
+#ifndef _PVARDIALOG_H_
+#define _PVARDIALOG_H_
+
+#include <QDialog>
 #include <QPushButton>
+#include <QPlainTextEdit>
+#include <QListWidget>
+#include <QVector>
 
-#include "PGetNormValDialog.h"
-
-//------------------------------------------------------------------------------
-PGetNormValDialog::PGetNormValDialog(double dval, QWidget *parent, Qt::WindowFlags f) :
-  QDialog(parent, f), fValue(dval)
+//-----------------------------------------------------------------------------
+struct PCollInfo
 {
-  QVBoxLayout *vbox = new QVBoxLayout;
-  QHBoxLayout *hbox1 = new QHBoxLayout;
-  QHBoxLayout *hbox2 = new QHBoxLayout;
+  QString fCollName;
+  QStringList fVarName;
+};
 
-  vbox->addLayout(hbox1);
-  vbox->addLayout(hbox2);
-
-  QLabel *lab = new QLabel("Norm Value: ");
-  QLineEdit *fEdit = new QLineEdit();
-  fEdit->setValidator(new QDoubleValidator());
-  fEdit->setText(QString("%1").arg(fValue));
-  hbox1->addWidget(lab);
-  hbox1->addWidget(fEdit);
-
-  QPushButton *ok = new QPushButton("OK");
-  QPushButton *cancel = new QPushButton("Cancel");
-  hbox2->addWidget(ok);
-  hbox2->addWidget(cancel);
-
-  setModal(true);
-
-  setLayout(vbox);
-
-  connect( fEdit, SIGNAL(textChanged(const QString&)), this, SLOT(gotValue(const QString&)));
-  connect( ok, SIGNAL(clicked()), this, SLOT(accept()));
-  connect( cancel, SIGNAL(clicked()), this, SLOT(reject()));
-}
-
-//------------------------------------------------------------------------------
-void PGetNormValDialog::gotValue(const QString& str)
+//-----------------------------------------------------------------------------
+class PShowVarNameDialog : public QDialog
 {
-  fValue = str.toDouble();
-}
+  Q_OBJECT
+
+  public:
+    PShowVarNameDialog(PCollInfo &info);
+};
+
+//-----------------------------------------------------------------------------
+class PVarDialog : public QDialog
+{
+  Q_OBJECT
+
+  public:
+    PVarDialog(QVector<PCollInfo> collection_list, bool darkTheme,
+               QWidget *parent = nullptr,
+               Qt::WindowFlags f = Qt::WindowFlags());
+
+  private:
+    QPlainTextEdit *fVarEdit;
+    QListWidget *fCollectionView;
+    QPushButton *fCancel;
+    QPushButton *fAdd;
+    QPushButton *fCheck;
+    QPushButton *fHelp;
+    QPushButton *fShowVarName;
+
+    QVector<PCollInfo> fCollList;
+
+    bool basic_check();
+    bool var_consistency_check();
+    QStringList collectVarNames(QStringList &list, bool& ok);
+    bool hasErrorDef(QStringList &varNames, QString& name);
+
+  private slots:
+    void check();
+    void add();
+    void help();
+    void showVarNames();
+
+  signals:
+    void check_request(QString varStr, QVector<int> idx);
+    void add_request(QString varStr, QVector<int> idx);
+};
+
+#endif // _PVARDIALOG_H_
diff --git a/src/musredit_qt5/mupp/PmuppGui.cpp b/src/musredit_qt5/mupp/PmuppGui.cpp
index cd32b288..c8186777 100644
--- a/src/musredit_qt5/mupp/PmuppGui.cpp
+++ b/src/musredit_qt5/mupp/PmuppGui.cpp
@@ -59,7 +59,6 @@
 
 #include "mupp_version.h"
 #include "PmuppGui.h"
-#include "PGetNormValDialog.h"
 
 //----------------------------------------------------------------------------------------------------
 /**
@@ -211,7 +210,8 @@ PmuppGui::PmuppGui( QStringList fln, QWidget *parent, Qt::WindowFlags f )
   fNormalizeAction = nullptr;
 
   fNormalize = false;
-  fNormVal = 0.0;
+
+  fVarDlg = nullptr;
 
   fMacroPath = QString("./");
   fMacroName = QString("");
@@ -549,16 +549,25 @@ void PmuppGui::setupToolActions()
 
   menu->addSeparator();
 
+  a = new QAction(tr( "Add Variable" ), this );
+  a->setStatusTip( tr("Calls a dialog which allows to add variables which are expressions of db/dat vars.") );
+  connect( a, SIGNAL( triggered() ), this, SLOT( addVar() ));
+  menu->addAction(a);
+
+  menu->addSeparator();
+
   fNormalizeAction = new QAction(tr( "Normalize" ), this);
   fNormalizeAction->setStatusTip( tr("Plot Data Normalized (y-axis)") );
   fNormalizeAction->setCheckable(true);
   connect( fNormalizeAction, SIGNAL( changed() ), this, SLOT( normalize() ) );
   menu->addAction(fNormalizeAction);
 
+/* //as35 - eventually also remove PGetNormValDialog.* from the source
   a = new QAction(tr( "Normalize by Value" ), this);
   a->setStatusTip( tr("Normalize by Value") );
   connect( a, SIGNAL( triggered() ), this, SLOT( normVal() ) );
   menu->addAction(a);
+*/
 }
 
 //----------------------------------------------------------------------------------------------------
@@ -705,27 +714,6 @@ void PmuppGui::normalize()
   fNormalize = fNormalizeAction->isChecked();
 }
 
-//----------------------------------------------------------------------------------------------------
-void PmuppGui::normVal()
-{
-  PGetNormValDialog *dlg = new PGetNormValDialog(fNormVal);
-  if (dlg == nullptr) {
-    QMessageBox::critical(this, "**ERROR**", "Couldn't invoke dialog, sorry :-(", QMessageBox::Ok, QMessageBox::NoButton);
-    return;
-  }
-
-  dlg->exec();
-
-  if (dlg->result() != QDialog::Accepted) {
-    delete dlg;
-    return;
-  }
-
-  fNormVal = dlg->getValue();
-
-  delete dlg;
-}
-
 //----------------------------------------------------------------------------------------------------
 /**
  * @brief PmuppGui::helpCmds
@@ -733,6 +721,7 @@ void PmuppGui::normVal()
 void PmuppGui::helpCmds()
 {
   QMessageBox::information(this, "cmd help", "<b>help:</b> this help.<br>"\
+                           "<b>add var</b>: allows to add a variable which is formula of collection vars.<br>"\
                            "<b>ditto</b>: addX/Y for the new selection as for the previous ones.<br>"\
                            "<b>dump collections:</b> dumps all currently loaded collections.<br>"\
                            "<b>dump XY:</b> dumps X/Y tree.<br>"\
@@ -1244,6 +1233,76 @@ void PmuppGui::addDitto()
   fColList->clearSelection();
 }
 
+//----------------------------------------------------------------------------------------------------
+void PmuppGui::addVar()
+{
+  // create collection list
+  QVector<PCollInfo> collection_list;
+
+  // go through all available collections and obtain the needed information
+  PCollInfo collInfo;
+  for (int i=0; i<fParamDataHandler->GetNoOfCollections(); i++) {
+    // get collection name
+    collInfo.fCollName = fParamDataHandler->GetCollectionName(i);
+    // get variable names
+    for (int j=0; j<fParamDataHandler->GetCollection(i)->GetRun(0).GetNoOfParam(); j++) {
+      collInfo.fVarName << fParamDataHandler->GetCollection(i)->GetRun(0).GetParam(j).GetName();
+    }
+    collection_list.push_back(collInfo);
+  }
+
+  // call variable dialog
+  if (fVarDlg == nullptr) {
+    fVarDlg = new PVarDialog(collection_list, fDarkTheme);
+    connect(fVarDlg, SIGNAL(check_request(QString,QVector<int>)), this, SLOT(check(QString,QVector<int>)));
+    connect(fVarDlg, SIGNAL(add_request(QString,QVector<int>)), this, SLOT(add(QString,QVector<int>)));
+  }
+  fVarDlg->show();
+
+}
+
+//----------------------------------------------------------------------------------------------------
+void PmuppGui::check(QString varStr, QVector<int> idx)
+{
+  int count = 0;
+  for (int i=0; i<idx.size(); i++) {
+    PVarHandler var_check(fParamDataHandler->GetCollection(i), varStr.toLatin1().data());
+    if (var_check.isValid()) {
+      count++;
+    } else {
+      // get error messages
+      QString mupp_err = QString("%1/.musrfit/mupp/mupp_err.log").arg(QString(qgetenv("HOME")));
+      QFile fin(mupp_err);
+      QString errStr("");
+      if (fin.open(QIODevice::ReadOnly | QIODevice::Text)) {
+        QTextStream in(&fin);
+        while (!in.atEnd()) {
+          errStr += in.readLine();
+          errStr += "\n";
+        }
+      }
+      fin.close();
+      QFile::remove(mupp_err);
+
+      if (errStr.isEmpty())
+        errStr = "unknown error - should never happen.";
+      QString msg = QString("Parse error(s):\n");
+      msg += errStr;
+      QMessageBox::critical(this, "**ERROR**", msg);
+      return;
+    }
+  }
+  if (count == idx.size()) {
+    QMessageBox::information(this, "**INFO**", "Parsing successful.");
+  }
+}
+
+//----------------------------------------------------------------------------------------------------
+void PmuppGui::add(QString varStr, QVector<int> idx)
+{
+
+}
+
 //----------------------------------------------------------------------------------------------------
 /**
  * @brief PmuppGui::findValue
@@ -1765,13 +1824,9 @@ void PmuppGui::plot()
       double max=0.0;
       for (int k=0; k<yyy.size(); k++) {
         max=0.0;
-        if (fNormVal == 0.0) {
-          for (int j=0; j<xx.size(); j++) {
-            if (yyy[k][j] > max)
-              max = yyy[k][j];
-          }
-        } else {
-          max = fNormVal;
+        for (int j=0; j<xx.size(); j++) {
+          if (yyy[k][j] > max)
+            max = yyy[k][j];
         }
         for (int j=0; j<xx.size(); j++) {
           yyy[k][j] /= max;
@@ -1998,6 +2053,8 @@ void PmuppGui::handleCmds()
       QMessageBox::critical(this, "**ERROR**", "found wrong norm cmd, will ignore it.");
       return;
     }
+  } else if (cmd.startsWith("add var")) {
+    addVar();
   } else if (cmd.startsWith("flush")) {
     fCmdHistory.clear();
     fCmdLine->setText("$ ");
@@ -2190,48 +2247,32 @@ QString PmuppGui::substituteDefaultLabels(QString label)
     result =QString("E (keV)");
   } else if (!label.compare("sigma", Qt::CaseInsensitive)) {
     if (fNormalize) {
-      if (fNormVal == 0.0)
-        result = QString("#sigma/max(#sigma)");
-      else
-        result = QString("#sigma/%1 (1/#mus)").arg(fNormVal);
+      result = QString("#sigma/max(#sigma)");
     } else {
       result = QString("#sigma (1/#mus)");
     }
   } else if (!label.compare("lambda", Qt::CaseInsensitive)) {
     if (fNormalize) {
-      if (fNormVal == 0.0)
-        result = QString("#lambda/max(#lambda)");
-      else
-        result = QString("#lambda/%1 (1/#mus)").arg(fNormVal);
+      result = QString("#lambda/max(#lambda)");
     } else {
       result = QString("#lambda (1/#mus)");
     }
   } else if (!label.compare("alpha_LR", Qt::CaseInsensitive)) {
     if (fNormalize) {
-      if (fNormVal == 0.0)
-        result = QString("#alpha_{LR}/max(#alpha_{LR})");
-      else
-        result = QString("#alpha_{LR}/%1").arg(fNormVal);
+      result = QString("#alpha_{LR}/max(#alpha_{LR})");
     } else {
       result = QString("#alpha_{LR}");
     }
   } else if (!label.compare("alpha_TB", Qt::CaseInsensitive)) {
     if (fNormalize) {
-      if (fNormVal == 0.0)
-        result = QString("#alpha_{TB}/max(#alpha_{TB})");
-      else
-        result = QString("#alpha_{TB}/%1").arg(fNormVal);
+      result = QString("#alpha_{TB}/max(#alpha_{TB})");
     } else {
       result = QString("#alpha_{TB}");
     }
   } else {
     if (fNormalize) {
-      if (fNormVal == 0.0) {
-        result = QString("Normalized ");
-        result += label;
-      } else {
-        result = QString("%1/%2").arg(label).arg(fNormVal);
-      }
+      result = QString("Normalized ");
+      result += label;
     }
   }
 
diff --git a/src/musredit_qt5/mupp/PmuppGui.h b/src/musredit_qt5/mupp/PmuppGui.h
index fa3f8ea2..d714f442 100644
--- a/src/musredit_qt5/mupp/PmuppGui.h
+++ b/src/musredit_qt5/mupp/PmuppGui.h
@@ -45,11 +45,13 @@
 #include <QEvent>
 #include <QProcess>
 
+#include "PVarHandler.h"
+#include "PVarDialog.h"
 #include "PmuppAdmin.h"
 #include "Pmupp.h"
 #include "mupp.h"
 
-//----------------------------------------------------------------------------------------------
+//-----------------------------------------------------------------------------
 class PmuppXY
 {
 public:
@@ -78,7 +80,7 @@ private:
   void init();
 };
 
-//----------------------------------------------------------------------------------------------
+//-----------------------------------------------------------------------------
 // Layout Scheme of PmuppGui:
 // |--------------------------------------------------------------------|
 // | Main                                                               |
@@ -96,9 +98,11 @@ private:
 // | |----------------------------------------------------------------| |
 // ----------------------------------------------------------------------
 //
-// Grid Left  contains: fColLabel, fColParamSplitter, fRemoveCollection, fRefreshCollection
-// Grid Right contains: f(X,Y)axisLabel, fView(X,Y), fAdd(X,Y), fRemove(X,Y), fAddDitto, fPlot
-//----------------------------------------------------------------------------------------------
+// Grid Left  contains: fColLabel, fColParamSplitter,
+//                      fRemoveCollection, fRefreshCollection
+// Grid Right contains: f(X,Y)axisLabel, fView(X,Y), fAdd(X,Y), fRemove(X,Y),
+//                      fAddDitto, fPlot
+//-----------------------------------------------------------------------------
 class PmuppGui : public QMainWindow
 {
   Q_OBJECT
@@ -115,8 +119,8 @@ public slots:
 
   void toolDumpCollections();
   void toolDumpXY();
+  void addVar();
   void normalize();
-  void normVal();
 
   void helpCmds();
   void helpAbout();
@@ -132,13 +136,13 @@ private:
   bool fDarkTheme;
   bool fDarkToolBarIcon;
   bool fNormalize;
-  double fNormVal;
 
   uint fDatime;
   uint fMuppInstance;
 
   PParamDataHandler *fParamDataHandler;
   QVector<PmuppXY> fXY;
+  QVector<PVarHandler> fVarHandler;
 
   QString fMacroPath;
   QString fMacroName;
@@ -178,6 +182,8 @@ private:
 
   QVector<QString> fCmdHistory;
 
+  PVarDialog *fVarDlg;
+
   QProcess *fMuppPlot;
 
   void setupFileActions();
@@ -198,34 +204,37 @@ private:
   void selectCollection(QString cmd);
   uint getFirstAvailableMuppInstance();
 
-private slots:
-  void refresh();
-  void remove();
-  void addX(QString param="");
-  void addY(QString param="");
-  void removeX(QString param="");
-  void removeY(QString param="");
-  void addDitto();
-  void createMacro();
-  void plot();
-  void handleCmds();
-
-  void handleNewData();
   void updateCollectionList();
-  void updateParamList(int currentRow);
   void updateXYList(int idx);
   void updateXYListGui();
-  void editCollName(QListWidgetItem *item);
-  void dropOnViewX(QListWidgetItem *item);
-  void dropOnViewY(QListWidgetItem *item);
-  void refreshY();
-
   bool findValue(PmuppRun &run, EAxis tag);
   bool allXYEqual();
   bool indexAlreadyPresent(int idx);
   void replaceIndex(PmuppXY &data, const int idx);
 
   void startMuppPlot();
+
+private slots:
+  void addDitto();
+  void addX(QString param="");
+  void addY(QString param="");
+  void createMacro();
+  void handleCmds();
+  void plot();
+  void refresh();
+  void remove();
+  void removeX(QString param="");
+  void removeY(QString param="");
+
+  void handleNewData();
+  void updateParamList(int currentRow);
+  void editCollName(QListWidgetItem *item);
+  void dropOnViewX(QListWidgetItem *item);
+  void dropOnViewY(QListWidgetItem *item);
+  void refreshY();
+
+  void check(QString varStr, QVector<int> idx);
+  void add(QString varStr, QVector<int> idx);
 };
 
 #endif // _PMUPPGUI_H_
diff --git a/src/musredit_qt5/mupp/PmuppScript.cpp b/src/musredit_qt5/mupp/PmuppScript.cpp
index 9305b9a6..2e12e6cc 100644
--- a/src/musredit_qt5/mupp/PmuppScript.cpp
+++ b/src/musredit_qt5/mupp/PmuppScript.cpp
@@ -807,8 +807,23 @@ int PmuppScript::var_cmd(const QString str)
   }
 
   PVarHandler varHandler(fParamDataHandler->GetCollection(idx), parse_str, tok[1].toLatin1().data());
-  if (!varHandler.isValid())
+  if (!varHandler.isValid()) {
+    // deal with errors
+    QString mupp_err = QString("%1/.musrfit/mupp/mupp_err.log").arg(QString(qgetenv("HOME")));
+
+    // dump error messages if present
+    QFile fout(mupp_err);
+    if (fout.open(QIODevice::ReadOnly | QIODevice::Text)) {
+      QString msg;
+      while (!fout.atEnd()) {
+        msg = fout.readLine();
+        std::cerr << msg.toLatin1().data();
+      }
+      // delete potentially present mupp_err.log file
+      QFile::remove(mupp_err);
+    }
     return 1;
+  }
   fVarHandler.push_back(varHandler);
 
   return 0;
diff --git a/src/musredit_qt5/mupp/mupp.qrc b/src/musredit_qt5/mupp/mupp.qrc
index dd5966e4..8390e2e1 100644
--- a/src/musredit_qt5/mupp/mupp.qrc
+++ b/src/musredit_qt5/mupp/mupp.qrc
@@ -4,6 +4,8 @@
     <file>icons/mupp-dark.svg</file>
     <file>icons/document-open-plain.svg</file>
     <file>icons/document-open-dark.svg</file>
+    <file>icons/varEdit-plain.svg</file>
+    <file>icons/varEdit-dark.svg</file>
     <file>icons/mupp.icns</file>
     <file>mupp_startup.xml.in</file>
   </qresource>
diff --git a/src/musredit_qt5/mupp/var/include/PErrorHandler.hpp b/src/musredit_qt5/mupp/var/include/PErrorHandler.hpp
index 214a386d..7c127ed2 100644
--- a/src/musredit_qt5/mupp/var/include/PErrorHandler.hpp
+++ b/src/musredit_qt5/mupp/var/include/PErrorHandler.hpp
@@ -34,6 +34,7 @@
 #define _PERROR_HANDLER_HPP_
 
 #include <iostream>
+#include <fstream>
 #include <string>
 #include <vector>
 
@@ -59,15 +60,19 @@ namespace mupp
      {
        int line;
        Iterator line_start = get_pos(err_pos, line);
+       const char *homeStr = getenv("HOME");
+       char fln[1024];
+       sprintf(fln, "%s/.musrfit/mupp/mupp_err.log", homeStr);
+       std::ofstream fout(fln, std::ofstream::app);
        if (err_pos != last) {
-         std::cout << message << what << ':' << std::endl;
-         std::cout << get_line(line_start) << std::endl;
+         fout << message << what << ':' << std::endl;
+         fout << get_line(line_start) << std::endl;
          for (; line_start != err_pos; ++line_start)
-           std::cout << ' ';
-         std::cout << "^~~" << std::endl;
+           fout << ' ';
+         fout << "^~~" << std::endl;
        } else {
-         std::cout << "**ERROR** Unexpected end of file. ";
-         std::cout << message << what << " line " << line << std::endl;
+         fout << "**ERROR** Unexpected end of file. ";
+         fout << message << what << " line " << line << std::endl;
        }
      }
 
diff --git a/src/musredit_qt5/mupp/var/include/PVarHandler.h b/src/musredit_qt5/mupp/var/include/PVarHandler.h
index 2e71288f..2ba4f1c9 100644
--- a/src/musredit_qt5/mupp/var/include/PVarHandler.h
+++ b/src/musredit_qt5/mupp/var/include/PVarHandler.h
@@ -42,15 +42,16 @@
 class PVarHandler {
   public:
     PVarHandler();
-    PVarHandler(PmuppCollection *coll, std::string parse_str, std::string var_name);
+    PVarHandler(PmuppCollection *coll, std::string parse_str, std::string var_name="");
 
     bool isValid() { return fIsValid; }
+    QString getCollName() { return fColl->GetName(); }
     QString getVarName() { return QString(fVarName.c_str()); }
     std::vector<double> getValues();
     std::vector<double> getErrors();
 
   private:
-    PmuppCollection *fColl; ///< collection need for parsing and evaluation
+    PmuppCollection *fColl; ///< collection needed for parsing and evaluation
     std::string fParseStr; ///< the variable input to be parsed
     std::string fVarName;  ///< variable name
     mupp::prog::PVarHandler fVar; ///< values of the evaluation
diff --git a/src/musredit_qt5/mupp/var/src/PVarHandler.cpp b/src/musredit_qt5/mupp/var/src/PVarHandler.cpp
index 9ac9c78a..af0c0710 100644
--- a/src/musredit_qt5/mupp/var/src/PVarHandler.cpp
+++ b/src/musredit_qt5/mupp/var/src/PVarHandler.cpp
@@ -74,15 +74,17 @@ PVarHandler::PVarHandler(PmuppCollection *coll, std::string parse_str, std::stri
         dataErr = getDataErr(i);
         prog.add_predef_var_values(getVarName(i), data, dataErr);
       }
-      mupp::prog::PProgEval eval(prog.getVars()); // setup evaluation stage
-      eval(fAst); // evaluate stuff
+      if (!fVarName.empty()) {
+        mupp::prog::PProgEval eval(prog.getVars()); // setup evaluation stage
+        eval(fAst); // evaluate stuff
 
-      // keep data
-      bool ok;
-      fVar = eval.getVar(fVarName, ok);
-      if (!ok) {
-        std::cerr << "**ERROR** evalution failed..." << std::endl;
-        fIsValid = false;
+        // keep data
+        bool ok;
+        fVar = eval.getVar(fVarName, ok);
+        if (!ok) {
+          std::cerr << "**ERROR** evalution failed..." << std::endl;
+          fIsValid = false;
+        }
       }
     }
     fIsValid = true;