diff --git a/ModelFit/mitkExpDecayOffsetModelTest_profile.json b/ModelFit/mitkExpDecayOffsetModelTest_profile.json
index 5686d33..7c2b2aa 100644
--- a/ModelFit/mitkExpDecayOffsetModelTest_profile.json
+++ b/ModelFit/mitkExpDecayOffsetModelTest_profile.json
@@ -1,22 +1,22 @@
 {
-  "parameterNames": [ "a", "b", "c" ],
+  "parameterNames": [ "y-intercept", "rate", "baseline" ],
   "numberOfParameters": 3,
   "parameterScales": [ 1.0, 1.0, 1.0 ],
-  "parameterUnits": [ "", "", "" ],
-  "derivedParameterNames": [ ],
+  "parameterUnits": [ "[unit of y]", "1/[unit of x]", "[unit of y]" ],
+  "derivedParameterNames": null,
   "numberOfDerivedParameters": 0,
-  "derivedParameterScales": [ ],
-  "derivedParameterUnits": [ ],
-  "staticParameterNames": [],
+  "derivedParameterScales": null,
+  "derivedParameterUnits": null,
+  "staticParameterNames": null,
   "numberOfStaticParameters": 0,
-  "staticParameterUnits": [],
+  "staticParameterUnits": null,
   "modelDisplayName": "Exponential Decay Offset Model",
   "modelType": "Generic",
-  "functionString": "a*exp(-1.0*x*b)+c",
+  "functionString": "y(x) = y-intercept * exp(-rate*x) + baseline",
   "classID": "ExpDecayOffsetModel",
   "xName": "x",
-  "xAxisName": "",
-  "xAxisUnit": "",
-  "yAxisName": "",
-  "yAxisUnit": ""
+  "xAxisName": "X",
+  "xAxisUnit": "unit of x",
+  "yAxisName": "Y",
+  "yAxisUnit": "unit of y"
 }
diff --git a/ModelFit/mitkT2DecayModelTest_modelValues.json b/ModelFit/mitkExponentialDecayModelTest_modelValues.json
similarity index 100%
rename from ModelFit/mitkT2DecayModelTest_modelValues.json
rename to ModelFit/mitkExponentialDecayModelTest_modelValues.json
diff --git a/ModelFit/mitkExponentialDecayModelTest_profile.json b/ModelFit/mitkExponentialDecayModelTest_profile.json
new file mode 100644
index 0000000..89997be
--- /dev/null
+++ b/ModelFit/mitkExponentialDecayModelTest_profile.json
@@ -0,0 +1,22 @@
+{
+  "parameterNames": [ "y-intercept", "lambda" ],
+  "numberOfParameters": 2,
+  "parameterScales": [ 1.0, 1.0 ],
+  "parameterUnits": [ "[unit of y]", "[unit of x]" ],
+  "derivedParameterNames": [ "rate" ],
+  "numberOfDerivedParameters": 1,
+  "derivedParameterScales": [ 1.0 ],
+  "derivedParameterUnits": [ "1/[unit of x]" ],
+  "staticParameterNames": null,
+  "numberOfStaticParameters": 0,
+  "staticParameterUnits": null,
+  "modelDisplayName": "Exponential Decay Model",
+  "modelType": "Generic",
+  "functionString": "y(x) = y-intercept * exp(-t/lambda)",
+  "classID": "ExponentialDecayModel",
+  "xName": "x",
+  "xAxisName": "X",
+  "xAxisUnit": "unit of x",
+  "yAxisName": "Y",
+  "yAxisUnit": "unit of y"
+}
diff --git a/ModelFit/mitkExponentialSaturationModelTest_profile.json b/ModelFit/mitkExponentialSaturationModelTest_profile.json
index 6f31bbb..ae3c7d1 100644
--- a/ModelFit/mitkExponentialSaturationModelTest_profile.json
+++ b/ModelFit/mitkExponentialSaturationModelTest_profile.json
@@ -1,22 +1,22 @@
 {
-  "parameterNames": [ "bat", "s0", "sfin", "rate" ],
+  "parameterNames": [ "onset", "baseline", "y_final", "rate" ],
   "numberOfParameters": 4,
   "parameterScales": [ 1.0, 1.0, 1.0, 1.0 ],
-  "parameterUnits": [ "", "", "", "" ],
+  "parameterUnits": [ "[unit of x]", "[unit of y]", "[unit of y]", "1/[unit of x]" ],
   "derivedParameterNames": null,
   "numberOfDerivedParameters": 0,
   "derivedParameterScales": null,
   "derivedParameterUnits": null,
   "staticParameterNames": null,
   "numberOfStaticParameters": 0,
   "staticParameterUnits": null,
   "modelDisplayName": "Exponential Saturation Model",
   "modelType": "Generic",
-  "functionString": "if x<BAT f(x) = S0 , else f(x) = A * (1-exp(-*B(x-BAT)))",
+  "functionString": "if x<onset: y(x) = baseline , else: y(x) = baseline + (y_final-baseline) * (1 - exp(-rate*(x-onset)))",
   "classID": "ExponentialSaturationModel",
-  "xName": "t",
-  "xAxisName": "",
-  "xAxisUnit": "",
-  "yAxisName": "",
-  "yAxisUnit": ""
+  "xName": "x",
+  "xAxisName": "X",
+  "xAxisUnit": "unit of x",
+  "yAxisName": "y",
+  "yAxisUnit": "unit of y"
 }
diff --git a/ModelFit/mitkLinearModelTest_profile.json b/ModelFit/mitkLinearModelTest_profile.json
index 09a7334..eb4c7a8 100644
--- a/ModelFit/mitkLinearModelTest_profile.json
+++ b/ModelFit/mitkLinearModelTest_profile.json
@@ -1,22 +1,22 @@
 {
-  "parameterNames": [ "slope", "offset" ],
+  "parameterNames": [ "slope", "y-intercept" ],
   "numberOfParameters": 2,
   "parameterScales": [ 1.0, 1.0 ],
-  "parameterUnits": [ "", "" ],
+  "parameterUnits": [ "[unit of y]/[unit of x]", "[unit of y]" ],
   "derivedParameterNames": [ "x-intercept" ],
   "numberOfDerivedParameters": 1,
   "derivedParameterScales": [ 1.0 ],
-  "derivedParameterUnits": [ "" ],
+  "derivedParameterUnits": [ "[unit of x]" ],
   "staticParameterNames": null,
   "numberOfStaticParameters": 0,
   "staticParameterUnits": null,
   "modelDisplayName": "Linear Model",
   "modelType": "Generic",
-  "functionString": "slope*x+offset",
+  "functionString": "y(x) = y-intercept + slope*x",
   "classID": "LinearModel",
   "xName": "x",
-  "xAxisName": "",
-  "xAxisUnit": "",
-  "yAxisName": "",
-  "yAxisUnit": ""
+  "xAxisName": "X",
+  "xAxisUnit": "unit of x",
+  "yAxisName": "Y",
+  "yAxisUnit": "unit of y"
 }
diff --git a/ModelFit/mitkT2DecayModelTest_profile.json b/ModelFit/mitkT2DecayModelTest_profile.json
deleted file mode 100644
index 9d56221..0000000
--- a/ModelFit/mitkT2DecayModelTest_profile.json
+++ /dev/null
@@ -1,22 +0,0 @@
-{
-  "parameterNames": [ "M0", "T2" ],
-  "numberOfParameters": 2,
-  "parameterScales": [1.0, 1.0],
-  "parameterUnits": [ "" , "" ],
-  "derivedParameterNames": [ "R2" ],
-  "numberOfDerivedParameters": 1,
-  "derivedParameterScales": [1.0],
-  "derivedParameterUnits": [""],
-  "staticParameterNames": null,
-  "numberOfStaticParameters": 0,
-  "staticParameterUnits":  null,
-  "modelDisplayName": "T2 Decay Model",
-  "modelType": "MRSignal",
-  "functionString": "M0 * exp(-t/T2)",
-  "classID": "T2DecayModel",
-  "xName": "t",
-  "xAxisName": "",
-  "xAxisUnit": "",
-  "yAxisName": "",
-  "yAxisUnit": ""
-}
diff --git a/ModelFit/mitkThreeStepLinearModelTest_modelValues.json b/ModelFit/mitkThreeStepLinearModelTest_modelValues.json
new file mode 100644
index 0000000..af12f59
--- /dev/null
+++ b/ModelFit/mitkThreeStepLinearModelTest_modelValues.json
@@ -0,0 +1,46 @@
+{
+  "modelValues": [
+    {
+      "modelParameterValues": [ 20.0, 100.0, 200.0, 5.0, 2.0 ],
+      "staticParameterValues": [],
+      "timeGrid": [ 0.0, 14.0, 28.0, 42.0, 56.0, 70.0, 84.0, 98.0, 112.0, 126.0, 140.0, 154.0, 168.0, 182.0, 196.0, 210.0, 224.0, 238.0, 252.0, 266.0, 280.0, 294.0 ],
+      "signal": [ 20.0, 20.0, 20.0, 20.0, 20.0, 20.0, 20.0, 20.0, 80.0, 150.0, 220.0, 290.0, 360.0, 430.0, 500.0, 540.0, 568.0, 596.0, 624.0, 652.0, 680.0, 708.0 ],
+      "derivedParameterValues": [ 86716.0, 294.0, 708.0, 708.0, -480.0, 120.0 ]
+    },
+    {
+      "modelParameterValues": [ 20.0, 100.0, 200.0, 5.0, -2.0 ],
+      "staticParameterValues": [],
+      "timeGrid": [ 0.0, 14.0, 28.0, 42.0, 56.0, 70.0, 84.0, 98.0, 112.0, 126.0, 140.0, 154.0, 168.0, 182.0, 196.0, 210.0, 224.0, 238.0, 252.0, 266.0, 280.0, 294.0 ],
+      "signal": [ 20.0, 20.0, 20.0, 20.0, 20.0, 20.0, 20.0, 20.0, 80.0, 150.0, 220.0, 290.0, 360.0, 430.0, 500.0, 500.0, 472.0, 444.0, 416.0, 388.0, 360.0, 332.0 ],
+      "derivedParameterValues": [ 68964.0, 294.0, 332.0, 520.0, -480.0, 920.0 ]
+    },
+    {
+      "modelParameterValues": [ 20.0, 100.0, 200.0, -5.0, 2.0 ],
+      "staticParameterValues": [],
+      "timeGrid": [ 0.0, 14.0, 28.0, 42.0, 56.0, 70.0, 84.0, 98.0, 112.0, 126.0, 140.0, 154.0, 168.0, 182.0, 196.0, 210.0, 224.0, 238.0, 252.0, 266.0, 280.0, 294.0 ],
+      "signal": [ 20.0, 20.0, 20.0, 20.0, 20.0, 20.0, 20.0, 20.0, -40.0, -110.0, -180.0, -250.0, -320.0, -390.0, -460.0, -460.0, -432.0, -404.0, -376.0, -348.0, -320.0, -292.0 ],
+      "derivedParameterValues": [ 61124.0, 294.0, -292.0, 20.0, 520.0, -880.0 ]
+    },
+    {
+      "modelParameterValues": [ 20.0, 100.0, 200.0, -2.0, 5.0 ],
+      "staticParameterValues": [],
+      "timeGrid": [ 0.0, 14.0, 28.0, 42.0, 56.0, 70.0, 84.0, 98.0, 112.0, 126.0, 140.0, 154.0, 168.0, 182.0, 196.0, 210.0, 224.0, 238.0, 252.0, 266.0, 280.0, 294.0 ],
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+      "derivedParameterValues": [ 21658.0, 294.0, 290.0, 290.0, 220.0, -1180.0 ]
+    },
+    {
+      "modelParameterValues": [ 20.0, 100.0, 200.0, -5.0, -2.0 ],
+      "staticParameterValues": [],
+      "timeGrid": [ 0.0, 14.0, 28.0, 42.0, 56.0, 70.0, 84.0, 98.0, 112.0, 126.0, 140.0, 154.0, 168.0, 182.0, 196.0, 210.0, 224.0, 238.0, 252.0, 266.0, 280.0, 294.0 ],
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+      "derivedParameterValues": [ 78876.0, 294.0, -668.0, 20.0, 520.0, -80.0 ]
+    },
+    {
+      "modelParameterValues": [ -20.0, 100.0, 200.0, 5.0, 2.0 ],
+      "staticParameterValues": [],
+      "timeGrid": [ 0.0, 14.0, 28.0, 42.0, 56.0, 70.0, 84.0, 98.0, 112.0, 126.0, 140.0, 154.0, 168.0, 182.0, 196.0, 210.0, 224.0, 238.0, 252.0, 266.0, 280.0, 294.0 ],
+      "signal": [ -20.0, -20.0, -20.0, -20.0, -20.0, -20.0, -20.0, -20.0, 40.0, 110.0, 180.0, 250.0, 320.0, 390.0, 460.0, 500.0, 528.0, 556.0, 584.0, 612.0, 640.0, 668.0 ],
+      "derivedParameterValues": [ 78876.0, 294.0, 668.0, 668.0, -520.0, 80.0 ]
+    }
+  ]
+}
diff --git a/ModelFit/mitkThreeStepLinearModelTest_profile.json b/ModelFit/mitkThreeStepLinearModelTest_profile.json
new file mode 100644
index 0000000..7b9aef0
--- /dev/null
+++ b/ModelFit/mitkThreeStepLinearModelTest_profile.json
@@ -0,0 +1,22 @@
+{
+  "parameterNames": [ "baseline", "x_changepoint1", "x_changepoint2", "slope1", "slope2" ],
+  "numberOfParameters": 5,
+  "parameterScales": [ 1.0, 1.0, 1.0, 1.0, 1.0 ],
+  "parameterUnits": [ "[unit of y]", "[unit of x]", "[unit of x]", "[unit of y]/[unit of x]", "[unit of y]/[unit of x]" ],
+  "derivedParameterNames": [ "auc", "x_final", "y_final", "y_max", "y-intercept1", "y-intercept2" ],
+  "numberOfDerivedParameters": 6,
+  "derivedParameterScales": [ 1.0, 1.0, 1.0, 1.0, 1.0, 1.0 ],
+  "derivedParameterUnits": [ "[unit of x]*[unit of y]", "[unit of x]", "[unit of y]", "[unit of y]", "[unit of y]", "[unit of y]" ],
+  "staticParameterNames": [],
+  "numberOfStaticParameters": 0,
+  "staticParameterUnits": [],
+  "modelDisplayName": "Three Step Linear Model",
+  "modelType": "Generic",
+  "functionString": "if x < x_changepoint1: y(x) = baseline, else if x_changepoint1 <= x <= x_changepoint2: y(x) = y-intercept1 + slope1*x, else if x>x_changepoint2: y(x) = y-intercept2 + slope2*x",
+  "classID": "ThreeStepLinearModel",
+  "xName": "x",
+  "xAxisName": "X",
+  "xAxisUnit": "unit of x",
+  "yAxisName": "Y",
+  "yAxisUnit": "unit of y"
+}
diff --git a/ModelFit/mitkTwoStepLinearModelTest_modelValues.json b/ModelFit/mitkTwoStepLinearModelTest_modelValues.json
new file mode 100644
index 0000000..9a40e40
--- /dev/null
+++ b/ModelFit/mitkTwoStepLinearModelTest_modelValues.json
@@ -0,0 +1,64 @@
+{
+"modelValues": 
+[
+{
+  "modelParameterValues": [ 0.0, 100.0, 5.0, 2.0 ],
+  "staticParameterValues": [],
+  "timeGrid": [ 0.0, 14.0, 28.0, 42.0, 56.0, 70.0, 84.0, 98.0, 112.0, 126.0, 140.0, 154.0, 168.0, 182.0, 196.0, 210.0, 224.0, 238.0, 252.0, 266.0, 280.0, 294.0 ],
+  "signal": [ 0.0, 70.0, 140.0, 210.0, 280.0, 350.0, 420.0, 490.0, 524.0, 552.0, 580.0, 608.0, 636.0, 664.0, 692.0, 720.0, 748.0, 776.0, 804.0, 832.0, 860.0, 888.0],
+  "derivedParameterValues": [ 159600.0, 888.0, 888.0, 300.0 ]
+},
+{
+  "modelParameterValues": [ 0.0, 100.0, 5.0, -2.0 ],
+  "staticParameterValues": [],
+  "timeGrid": [ 0.0, 14.0, 28.0, 42.0, 56.0, 70.0, 84.0, 98.0, 112.0, 126.0, 140.0, 154.0, 168.0, 182.0, 196.0, 210.0, 224.0, 238.0, 252.0, 266.0, 280.0, 294.0 ],
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+  "derivedParameterValues": [ 84280.0, 112.0, 500.0, 700.0 ]
+},
+{
+  "modelParameterValues": [ 0.0, 100.0, -5.0, 2.0 ],
+  "staticParameterValues": [],
+  "timeGrid": [ 0.0, 14.0, 28.0, 42.0, 56.0, 70.0, 84.0, 98.0, 112.0, 126.0, 140.0, 154.0, 168.0, 182.0, 196.0, 210.0, 224.0, 238.0, 252.0, 266.0, 280.0, 294.0 ],
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+  "derivedParameterValues": [ 84280.0, -112.0, 0.0, -700.0 ]
+},
+{
+  "modelParameterValues": [ 0.0, 100.0, -2.0, 5.0 ],
+  "staticParameterValues": [],
+  "timeGrid": [ 0.0, 14.0, 28.0, 42.0, 56.0, 70.0, 84.0, 98.0, 112.0, 126.0, 140.0, 154.0, 168.0, 182.0, 196.0, 210.0, 224.0, 238.0, 252.0, 266.0, 280.0, 294.0 ],
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+  "derivedParameterValues": [ 73206.0, 770.0, 770.0, -700.0 ]
+},
+{
+  "modelParameterValues": [ 0.0, 100.0, -5.0, -2.0 ],
+  "staticParameterValues": [],
+  "timeGrid": [ 0.0, 14.0, 28.0, 42.0, 56.0, 70.0, 84.0, 98.0, 112.0, 126.0, 140.0, 154.0, 168.0, 182.0, 196.0, 210.0, 224.0, 238.0, 252.0, 266.0, 280.0, 294.0 ],
+  "signal": [ 0.0, -70.0, -140.0, -210.0, -280.0, -350.0, -420.0, -490.0, -524.0, -552.0, -580.0, -608.0, -636.0, -664.0, -692.0, -720.0, -748.0, -776.0, -804.0, -832.0, -860.0, -888.0 ],
+  "derivedParameterValues": [ 159600.0, -888.0, 0.0, -300.0 ]
+},
+{
+  "modelParameterValues": [ 0.0, -100.0, 5.0, 2.0 ],
+  "staticParameterValues": [],
+  "timeGrid": [ 0.0, 14.0, 28.0, 42.0, 56.0, 70.0, 84.0, 98.0, 112.0, 126.0, 140.0, 154.0, 168.0, 182.0, 196.0, 210.0, 224.0, 238.0, 252.0, 266.0, 280.0, 294.0 ],
+  "signal": [ -300.0, -272.0, -244.0, -216.0, -188.0, -160.0, -132.0, -104.0, -76.0, -48.0, -20.0, 8.0, 36.0, 64.0, 92.0, 120.0, 148.0, 176.0, 204.0, 232.0, 260.0, 288.0 ],
+  "derivedParameterValues": [ 43204.0, 288.0, 288.0, -300.0 ]
+},
+{
+  "modelParameterValues": [ 100.0, 100.0, 5.0, 2.0  ],
+  "staticParameterValues": [],
+  "timeGrid": [ 0.0, 14.0, 28.0, 42.0, 56.0, 70.0, 84.0, 98.0, 112.0, 126.0, 140.0, 154.0, 168.0, 182.0, 196.0, 210.0, 224.0, 238.0, 252.0, 266.0, 280.0, 294.0 ],
+  "signal": [ 100.0, 170.0, 240.0, 310.0, 380.0, 450.0, 520.0, 590.0, 624.0, 652.0, 680.0, 708.0, 736.0, 764.0, 792.0, 820.0, 848.0, 876.0, 904.0, 932.0, 960.0, 988.0 ],
+  "derivedParameterValues": [ 189000.0, 988.0, 988.0, 400.0 ]
+},
+{
+  "modelParameterValues": [ -100.0, 100.0, 5.0, 2.0 ],
+  "staticParameterValues": [],
+  "timeGrid": [ 0.0, 14.0, 28.0, 42.0, 56.0, 70.0, 84.0, 98.0, 112.0, 126.0, 140.0, 154.0, 168.0, 182.0, 196.0, 210.0, 224.0, 238.0, 252.0, 266.0, 280.0, 294.0 ],
+  "signal": [ -100.0, -30.0, 40.0, 110.0, 180.0, 250.0, 320.0, 390.0, 424.0, 452.0, 480.0, 508.0, 536.0, 564.0, 592.0, 620.0, 648.0, 676.0, 704.0, 732.0, 760.0, 788.0 ],
+  "derivedParameterValues": [ 132020.0, 788.0, 788.0, 200.0 ]
+}
+]
+}
+
+
+
diff --git a/ModelFit/mitkTwoStepLinearModelTest_profile.json b/ModelFit/mitkTwoStepLinearModelTest_profile.json
new file mode 100644
index 0000000..5e9f89a
--- /dev/null
+++ b/ModelFit/mitkTwoStepLinearModelTest_profile.json
@@ -0,0 +1,22 @@
+{
+  "parameterNames": [ "y-intercept", "x_changepoint", "slope1", "slope2" ],
+  "numberOfParameters": 4,
+  "parameterScales": [ 1.0, 1.0, 1.0, 1.0 ],
+  "parameterUnits": [ "[unit of y]", "[unit of x]", "[unit of y]/[unit of x]", "[unit of y]/[unit of x]" ],
+  "derivedParameterNames": [ "auc", "y_final", "y_max", "y-intercept1" ],
+  "numberOfDerivedParameters": 4,
+  "derivedParameterScales": [ 1.0, 1.0, 1.0, 1.0 ],
+  "derivedParameterUnits": [ "[unit of x]*[unit of y]", "[unit of y]", "[unit of y]", "[unit of y]" ],
+  "staticParameterNames": null,
+  "numberOfStaticParameters": 0,
+  "staticParameterUnits": null,
+  "modelDisplayName": "Two Step Linear Model",
+  "modelType": "Generic",
+  "functionString": "if x < x_changepoint: y(x) = y-intercept + slope1*x, else: y(x) = y-intercept1 + slope2*x",
+  "classID": "TwoStepLinearModel",
+  "xName": "x",
+  "xAxisName": "X",
+  "xAxisUnit": "unit of x",
+  "yAxisName": "Y",
+  "yAxisUnit": "unit of y"
+}