diff --git a/src/SimNDT/core/constants.py b/src/SimNDT/core/constants.py
new file mode 100644
index 0000000..f4a59d2
--- /dev/null
+++ b/src/SimNDT/core/constants.py
@@ -0,0 +1,29 @@
+__author__ = 'Miguel Molero'
+
+
+class BC(object):
+	AbsorbingLayer = 0
+	AirLayer = 1
+	keys = ["Absorbing", "Air"]
+
+class WaveSource(object):
+	Longitudinal = 0
+	Shear = 1
+	LongitudinalAndShear = 2
+	keys = ['Longitudinal', 'Shear', 'LongitudinalAndShear']
+
+
+class TypeSource(object):
+
+	Pressure = 0
+	Displacement = 1
+	PressureAndDisplacement = 2
+	keys = ["Pressure", "Displacement", "PressureAndDisplacement"]
+
+
+class SignalType(object):
+	RaisedCosinePulse = 0
+	GaussianSinePulse = 1
+
+
+