Working with Multidimensional Data
A cellset is the result of a query on multidimensional data. It consists of a collection of axes, usually no more than four axes and typically only two or three. An axis is a collection of members from one or more dimensions, which is used to locate or filter specific values in a cube.
A position is a point along an axis. For an axis consisting of a single dimension, these positions are a subset of the dimension members. If an axis consists of more than one dimension, then each position is a compound entity, which has n parts where n is the number of dimensions oriented along that axis. Each part of the position is a member from one constituent dimension.
For example, if the Geography and Product dimensions from a cube containing sales data are oriented along the xaxis of a cellset, a position along this axis may contain the members "USA" and "Computers." In this example, determining a position along the xaxis requires that members from each dimension are oriented along the axis.
A cell is an object positioned at the intersection of axis coordinates. Each cell has multiple pieces of information associated with it, including the data itself, a formatted string (the displayable form of cell data), and the cell ordinal value. (Each cell is a unique ordinal value in the cellset. The ordinal value of the first cell in the cellset is zero, while the leftmost cell in the second row of a cellset with eight columns would have an ordinal value of eight.)
For example, a cube has the following six dimensions (note that this cube schema differs slightly from the example given in Overview of Multidimensional Schemas and Data):

Salesperson

Geography (natural hierarchy) — Continents, Countries, States, and so on

Quarters — Quarters, Months, Days

Years

Measures — Sales, PercentChange, BudgetedSales

Products
The following cellset represents sales for 1991 for all products:
Note 

The cell values in the example can be viewed as ordered pairs of axis position ordinals where the first digit represents the xaxis position and the second digit the yaxis position. 
The characteristics of this cellset are as follows:

Axis dimensions: Quarters, Salesperson, Geography

Filter dimensions: Measures, Years, Products

Two axes: COLUMN (x, or Axis 0) and ROW (y, or Axis 1)

xaxis: two nested dimensions, Salesperson and Geography

yaxis: Quarters dimension
The xaxis has two nested dimensions: Salesperson and Geography. From Geography, four members are selected: Seattle, Boston, USASouth, and Japan. Two members are selected from Salesperson: Valentine and Nash. This yields a total of eight positions on this axis (8 = 4*2).
Each coordinate is represented as a position with two members — one from the Salesperson dimension and another from the Geography dimension:
(Valentine, Seattle), (Valentine, Boston), (Valentine, USA_North), (Valentine, Japan), (Nash, Seattle), (Nash, Boston), (Nash, USA_North), (Nash, Japan)
The yaxis has only one dimension, containing the following eight positions:
Jan, Feb, Mar, Qtr2, Qtr3, Oct, Nov, Dec
Cellsets, cells, axes, and positions are all represented in ADO MD by corresponding objects: Cellset, Cell, Axis, and Position.