Update README.md

added more informations about the file types.

README.md

@@ -15,3 +15,36 @@ This project is a collection of libraries and helpers to simplify the process of
  * stl: Für 3D-Daten, tesseliertes, weit verbreitetes Format, große Datenmenge
  * wrl/vrml: Für 3D-Daten, tesseliertes und komprimiertes Format mit Texturen
  * 3dxml: Für 3D-Daten, neues tesseliertes Format von Dassault, kostenloser Viewer
+
+##Format 
+
+#iges/iges
+
+* supports the following models: circuit diagrams, wireframe, freeform surface or solid modeling representations.
+* single parts are stored as entities (https://de.wikipedia.org/wiki/Initial_Graphics_Exchange_Specification)
+* files can be saved in ascii and binary format, however the last one is not supported anymore.
+
+#stp/step
+
+* wide spread
+* files are saved in ascii
+* one instance/part per line is the convention, but multiple files can be saved in one line
+* defined in ISO 10303-21, better walk away?
+* ISO 10303-21 defines the encoding mechanism on how to represent data according to a given EXPRESS schema, but not the EXPRESS schema itself.
+
+#stl
+
+* wide spread
+* standard use case rapid prototyping, 3D printing and computer-aided manufacturing
+* describe only the surface geometry of a three-dimensional object without any representation of color, texture or other common CAD model attributes
+* supports acsii and binary formats
+
+#wrl/vrml
+
+* is a standard file format for representing 3-dimensional (3D) interactive vector graphics
+* has been superseded by X3D(iso standard)
+
+#3dxml
+* uses xml to describe 3D geometries
+* no to be confused with x3D 
+* 3DXML format is only supported by Dassault Systèmes product line