15. A computer readable memory device including software that when executed by a processor is operable to: create a plurality of first models according to a second model including elements with information defining a structure and hierarchical arrangement of elements for the first models; associate elements of the second model with a presentation policy model including presentation policies, wherein the presentation policies indicate display characteristics controlling a visual appearance for presented elements; apply the presentation policies to the elements of the first models to generate a corresponding presentation model for each of the first models based on the association between the elements of the second model and the presentation policy model, wherein the corresponding presentation models provide different customized for the first models and corresponding model entities created from those first models, and wherein each presentation model associates each of one or more individual elements of a corresponding first model with one or more corresponding display characteristics controlling a visual appearance of a presented element; create a model entity according to a first model, wherein the model entity includes actual data pertaining to an entity and the first model includes elements with information defining a structure and hierarchical arrangement of elements for the model entity; read model content from said first model and read presentation data from said corresponding presentation model; and apply the read model content and presentation data to said model entity including the actual data to present elements of the model entity with a visual appearance in accordance with the associated display characteristics of corresponding individual elements of the first model, wherein at least two elements of the model entity are presented with different display characteristics within a presentation.
15. A computer readable memory device including software that when executed by a processor is operable to: create a plurality of first models according to a second model including elements with information defining a structure and hierarchical arrangement of elements for the first models; associate elements of the second model with a presentation policy model including presentation policies, wherein the presentation policies indicate display characteristics controlling a visual appearance for presented elements; apply the presentation policies to the elements of the first models to generate a corresponding presentation model for each of the first models based on the association between the elements of the second model and the presentation policy model, wherein the corresponding presentation models provide different customized for the first models and corresponding model entities created from those first models, and wherein each presentation model associates each of one or more individual elements of a corresponding first model with one or more corresponding display characteristics controlling a visual appearance of a presented element; create a model entity according to a first model, wherein the model entity includes actual data pertaining to an entity and the first model includes elements with information defining a structure and hierarchical arrangement of elements for the model entity; read model content from said first model and read presentation data from said corresponding presentation model; and apply the read model content and presentation data to said model entity including the actual data to present elements of the model entity with a visual appearance in accordance with the associated display characteristics of corresponding individual elements of the first model, wherein at least two elements of the model entity are presented with different display characteristics within a presentation. 20. The memory device of claim 15 , wherein a presentation policy includes a model property expression and presentation form thereof indicating said display characteristics, said presentation form including at least one of a node icon, word background, word format, size, color, and the color, thickness and form of lines that connect nodes.