Represents a single unique copy a of an associated logical volume in geometrical hierarchy Represents a division of the associated logical volume in geometrical hierarchy Represents a top of a geometrical sub-hierarchy not placed in space None of its children can coincide with its boundary defined by an associated solid Two different placements of the same logical volume represent two different geometrical hierarchies in space Allows to create a group of volumes bound together without a boundary All the volumes exits inside the same virtual reference system of the assmebly volume they belong to When assembly volume is placed all its children follow the global transformation applied to their assembly volume After the assembly volume is placed its children exist as standalone placements in space independent of each other Base type for logical surfaces (for the moment only optical) Abstract element for all solids substitution group Surface between two physical volumes Surface between two physical volumes Definitions of a geometrical hierarchy of a set of volumes Geometry setup representing the particular geometry hierarchy by refferring to a given volume which becomes the top level volume A reference to the previously defined volume in the structure block chosen by this setup World volumme can't be an assembly volume The GDML Schema version consists of 3 digits X.Y.Z where these mean: X - major number, increased when major new features or backward incompatible bug fixes are added and means the GDML Processor is allowed to refuse processing of such a document if this is using the more recent version of the GDML Schema then GDML Processor understands Y - minor number, increased when incremental and backward compatible changes or improvements are made into the GDML Schema. GDML Processor should be able to process such a document using higher minor version number then that of the GDML Processor Z - bugfix revision number, increased when fully backward compatible changes which resolve a problem in GDML Schema are applied