File Format FCStd

A FreeCAD project is actually a normal zip file that always contains a Document.xml file and optionally several data files, a GuiDocument.xml and a thumbnail in PNG format.

Structure of Document.xml
                <String value="/tmp/test.FCStd"/> </Property>  <String value="201b746f-a1ed-4297-bf3d-65d5ec11abe0"/> </Property>  <String value="names"/> </Property>  <String value=""/> </Property>  <String value="Fri Jan 29 15:15:21 2010 "/> </Property> </Properties> <Objects Count="2"> <Object type="Mesh::Cube" name="Cube" /> <Object type="Part::Box" name="Box" /> </Objects> <ObjectData Count="2"> <Object name="Cube"> <Properties Count="7">  <Float value="10"/> </Property>  <String value="Cube"/> </Property>  <Float value="10"/> </Property>  <Mesh file="MeshKernel.bms"/> </Property>   </Property>  <Link value=""/> </Property>  <Float value="10"/> </Property> </Properties> </Object> <Object name="Box"> <Properties Count="7">  <Float value="10"/> </Property>  <String value="Box2"/> </Property>  <Float value="10"/> </Property>  <PropertyPlacement Px="0" Py="0" Pz="0" Q0="0" Q1="0" Q2="0" Q3="1"/> </Property> <Property name="Pos" type="App::PropertyPlacementLink"> <Link value=""/> </Property> <Property name="Shape" type="Part::PropertyPartShape"> <Part file="PartShape.brp2"/> </Property> <Property name="Width" type="App::PropertyLength"> <Float value="10"/> </Property> </Properties> </Object> </ObjectData> </Document>

Other
More information on the format Fcstd.

Here, a file Converter utility ImageConv.