Grid Facet Concept 
A Grid Facet represents the mathematical concept of a facet  a 1codimensional entity (d1 dimensional) in a (ddimensional) Grid.
F is a type which is a model of Grid Facet.
f is an object of type F
C is a shorthand for the F::Cell type
c is an object of type C
g is an object of type F::grid_type
h is an object of type F::facet_handle
vf is an object of type F::VertexIterator
NOTE: The types and expression involving Incidence Iterators are given below for the case of vertexonfacet iteration. Analogous types and expressions can be defined for the other element types.
The tables are to be understood in the following sense:
If a facet defines the incidence iterator over vertices,
then the requirements under Optional part apply.
Analogous requirements take effect if `vertex' is replaced by another element type.
Name  Expression  Description 
handle type  F::facet_handle  type of the corresponding Facet Handle 
cell type 
F::Cell 
Cell type of the facet,
short for F::grid_type::Cell .

Optional part (as example)  
vertexonfacet iterator  F::VertexIterator  type of the corr. VertexOnFacetIterator 
Name  Expression  Type requirements  return type 
handle  f.handle()  F::facet_handle  
first cell 
c = f.C1()  Cell  
second cell 
c = f.C2()  Cell  
Optional part (as example)  
vertexonfacet iteration start  f.FirstVertex()  F::VertexIterator  
number of incident vertices  F.NumOfVertices()  int 
Name  Expression  Precondition  Semantics  Postcondition 
handle  h = f.handle();  f is valid  shorthand for h = f.TheGrid(). handle(f)  f == f.TheGrid(). facet(h) 
Optional part (as example)  
Vertexonfacet iteration start  vf = f.FirstVertex()  f is valid  let fi point to the first vertex incident to f  vf.TheEdge() == vf.TheAnchor() == f and vf.TheGrid() == f.TheGrid() 
number of incident vertices  n = f.NumOfVertices()  f is valid  n is the number of vertices that are incident to f 
All operations are amortized constant timeX.
Complex2D::Facet defined in edge2d.h (identical to Complex2D::Facet)
Grid Grid Element Handle Facet Handle Grid Element Grid Cell Sequence Iterator Incidence Iterator
Grid Facet Concept 