Abstract Entity is a class of Entitys that cannot have direct instances and represent aspects of entities.

It is the power instance of  Orderless Class, which means that its sub-types can belong to any Ordered Class.

Example:

1) Aspects of Entitys, such as Lexical Scope.

2) Propertys of Individuals.

A  Class of Entity is a Class of Element that classifies Entitys. Being a subtype of Entity, it is also an instance of itself.

Note:

1)   SysFEAT is a higher-order ontology, so   Class of Entity may have members that are also  Class of Entity (Class of Classes).

2)   SysFEAT is also a non-well-founded allows for self-referencing   Class of Entity.

 Concrete Entity is a class whose instances are classifed by an Ordered Class: it is the power instance of Ordered Class.

Examples:

- Particular Entity

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An  Entity is a distinct, identifiable Element that has a proper existence (living or non living). It is accessible by some referencing mechanism and can establish elementary relationships (Relationship) to other  Entitys.

 Entity is the powerinstance of Class of Entity: all subtypes of  Entity are instances of Class of Entity.

 First Order Class is defined as the  Meta-Class of all subclasses of Particular Entity.

Each instance of  First Order Class is a Class of Entity, each of whose instances is necessarily an Particular Entity.

A  Lexical Scope is a kind of Abstract Entity that defines the existence, visibility, and accessibility of the entities nested within it through a Nesting Relationship.

Nested Entitys have no independent identity or validity outside the lexical or structural scope in which they are defined - they exist only within and for the duration of their parent construct.

Every Entity belongs to exactly one  Lexical Scope.

A  Lexical Scope carries no intrinsic semantic meaning; it serves purely as a syntactic mechanism for establishing hierarchical containment.

Examples:

1) Composite structures nesting their internal constituents.

2) Social structures nesting their roles and functions.

3) Computer functions nesting their local variables or inner functions

4) Packages nesting their building blocks.

A  Meta Family of Class is a  Class of Classes of Element (its members are themselves Class of Elements), typically used to group or organize collections of Class of Elements that share some structural, relational, or definitional property.

In contrast to families of sets, which are sets of sets, a family of classes operates at a higher ontological level-its elements may represent universes, types, or conceptual groupings rather than individual sets.

 Meta-Class (also called  Class of Classes of Entity) is defined as the Class of Entity of all Class of Entitys each of whose instances is necessarily a Class of Entity.

In other word,  Meta-Class is the powertype of Class of Entity: all sub-classes of Class of Entitys are instances of  Meta-Class.

Since  Meta-Class is itself a sub-type of Class of Entity,  Meta-Class is an instance of itself.

 Orderless Meta-Class is the Meta-Class of Orderless Class.

All its instance are Class of Entitys that can belong to multiple level of powertyping, an allows some of the classes to be member of themselves.

A  Particular Entity is a Concrete Entity that is not itself a class (Class of Entity): it cannot have instances. The " Particular Entity" class is the powerinstance of First Order Class. 

 Particular Entitys are the most common type of entities.
Examples:

. The set of numbers {1,2,3,4}.

. The mathematical constant π (pi).

. The English word "Tree" (as a specific string of characters in a specific language).

. The Eiffel tower (31st March 1889 - ...).

. Mount Vesuvius eruption (Aug. 24-25, A.D. 79).

 Second Order Class is defined as the  Meta-Class of all subclasses of First Order Class.

Each instance of  Second Order Class is a class, each of whose instances is a First Order Class.

First Order Class is an instance of  Second Order Class since, by definition, all of its instances are First Order Classes.

Examples:

1) Car-Brand (with instances such as VolkswagenCar and HondaCar),

2) AnimalSpecies (with instancessuch as GreyWolf and Dodo), Occupation, and USArmyRank.