Add information on representation of metadata and topological relationships

[pshriwise]

There is some information in the developer's guide on what information exists in our .h5m files regarding metadata (meaning material/temperature assignments, boundary conditions, etc.).

It would be useful to developers to describe in more detail what tags are used (CATEGORY_TAG, GEOM_DIM, etc.), how the metadata is organized in the file ("Group" EntitySet's are tagged with X and contain Y).

Similarly, it would be useful for the developer's guide to contain information on how topological relationships are represented (parent-child relationships) and what each entity set requires to be recognized as a geometric entity (category tag and geom dim tag).

[pshriwise]

Adding an inventory of the tags we use to store topological information and metadata:

dagmc

Geometry

Tag Name	Type	Real Type	Size	Purpose	Tagged On
GLOBAL_ID	MB_TYPE_INT	int	1	Value of an ID associated with a geometric EntitySet.	EntitySet
GEOM_SENSE_2	EntityHandle	uint64_t	2	Relates a surface to the two volumes on either side of the surface. An entry in the first position indicates tht the surafce has a sense that is forward with respect to the volume EntityHandle in that position. An entry in the second position indicates that the surface has a sense reversed with respect to the volume EntityHandle in that position.
GEOM_SENSE_N_ENTS	EntityHandle	uint64_t	N	Relates a curve to any topologically adjacent surface EntitySets.	EntitySet
GEOM_SENSE_N_SENSES	MB_TYPE_INT	int	N	Curve sense data correllated with the GEOM_SENSE_N_ENTS information. Values are 1 for a forward senses and -1 for reversed senses.	EntitySet
CATEGORY	MB_TYPE_OPAQUE	char	32	The geometric category of an EntitySet. One of "Vertex", "Curve", "Surface", "Volume", or "Group"	EntitySet
GEOM_DIM	MB_TYPE_INT	int	1	The dimensionality of a geometric EntitySet. See table below for meaning of values.	EntitySet
NAME	MB_TYPE_OPAQUE	char	32	A name assigned to an EntitySet. Use to indicate material assignments, boundary conditions, temperatures, and the implicit complement on EntitySet's with a CATEGORY tag whose value is "Group"	EntitySet

Geometry Object	Dimensionality
Vertex	0
Curve	1
Surface	2
Volume	3
Group	4

Tree Structures

Tag Name	Type	True Type	Size	Purpose	Tagged On
OBB_ROOT	EntityHandle	uint64_t	1	This tag resides on geometric EntitySet's. Its value is the handle of the associated OBB tree root EntitySet.	EntitySet
OBB_GSET	EntityHandle	uint64_t	1	This tag resides on OBB tree root EntitySet's. Its value is the handle of the associated geometric EntitySet.	EntitySet
OBB	MB_TYPE_DOUBLE	double	9	This tag resides on EntitySets in an OBB tree. The value of this tag is nine doubles representing the oriented bounding box for this EntitySet-node in the tree.	EntitySet

[pshriwise]

Also linking in this set of slides that covers some of this as well as EntitySet relationships.

https://docs.google.com/presentation/d/10m8e6GN8DhLpNHHSOMniZ2pDU9DOAiD0xJF1Zyewzh8/edit?usp=sharing