Question: What type of entities are Jiangmen and Pingdu?

Context articles: Pingdu
Authentication protocol
Polymorphism (computer science)
Queue (abstract data type)
Corporate taxonomy
Object-oriented user interface
Jiangmen
Civic action program
Declaration (computer programming)
SGML entity

Pingdu () is the largest county-level city of Qingdao sub-provincial city, Shandong Province, China.
An authentication protocol is a type of computer communications protocol or cryptographic protocol specifically designed for transfer of authentication data between two entities.
 It allows to authenticate the connecting entity (e.g. Client connecting to a Server) as well as authenticate itself to the connecting entity (Server to a client) by declaring the type of information needed for authentication as well as syntax.
 It is the most important layer of protection needed for secure communication within computer networks.
In programming languages and type theory, polymorphism (from Greek πολύς, "polys", "many, much" and μορφή, "morphē", "form, shape") is the provision of a single interface to entities of different types.
 A polymorphic type is one whose operations can also be applied to values of some other type, or types.
 There are several fundamentally different kinds of polymorphism:
In computer science, a queue ( ) is a particular kind of abstract data type or collection in which the entities in the collection are kept in order and the principle (or only) operations on the collection are the addition of entities to the rear terminal position, known as "enqueue," and removal of entities from the front terminal position, known as "dequeue".
 This makes the queue a First-In-First-Out (FIFO) data structure.
 In a FIFO data structure, the first element added to the queue will be the first one to be removed.
 This is equivalent to the requirement that once a new element is added, all elements that were added before have to be removed before the new element can be removed.
 Often a "peek" or "front" operation is also entered, returning the value of the front element without dequeuing it.
 A queue is an example of a linear data structure, or more abstractly a sequential collection.
Corporate taxonomy is the hierarchical classification of entities of interest of an enterprise, organization or administration, used to classify documents, digital assets and other information.
 Taxonomies can cover virtually any type of physical or conceptual entities (products, processes, knowledge fields, human groups, etc.) at any level of granularity.
In computing, an object-oriented user interface (OOUI) is a type of user interface based on an object-oriented programming metaphor.
 In an OOUI, the user interacts explicitly with objects that represent entities in the domain that the application is concerned with.
 Many vector drawing applications, for example, have an OOUI – the objects being lines, circles and canvases.
 The user may explicitly select an object, alter its properties (such as size or colour), or invoke other actions upon it (such as to move, copy, or re-align it).
 If a business application has any OOUI, the user may be selecting and/or invoking actions on objects representing entities in the business domain such as customers, products or orders.
Jiangmen, formerly romanized in Cantonese as Kongmoon, is a prefecture-level city in Guangdong Province in southern China.
 Its 3 urban districts are now part of the Guangzhou–Shenzhen conurbation and the entire prefecture had a population of about 4.45 million in 2010.
A civic action program also known as civic action project is a type of operation designed to assist an area by using the capabilities and resources of a military force or civilian organization to conduct long-term programs or short-term projects.
 This type of operations include: dental civic action program (DENTCAP), engineering civic action program (ENCAP), medical civic action program (MEDCAP), and veterinarian civic action program (VETCAP).
 Entities of foreign nations usually conduct these operations at the invitation of a host nation.
In computer programming, a declaration is a language construct that specifies properties of an identifier: it declares what a word (identifier) "means:."
 Declarations are most commonly used for functions, variables, constants, and classes, but can also be used for other entities such as enumerations and type definitions.
 Beyond the name (the identifier itself) and the kind of entity (function, variable, etc.), declarations typically specify the data type (for variables and constants), or the type signature (for functions); types may also include dimensions, such as for arrays.
 A declaration is used to announce the existence of the entity to the compiler; this is important in those strongly typed languages that require functions, variables, and constants, and their types to be specified with a declaration before use, and is used in forward declaration.
 The term "declaration" is frequently contrasted with the term "definition", but meaning and usage varies significantly between languages; see below.
In the Standard Generalized Markup Language (SGML), an entity is a primitive data type, which associates a string with either a unique alias (such as a user-specified name) or an SGML reserved word (such as codice_1).
 Entities are foundational to the organizational structure and definition of SGML documents.
 The SGML specification defines numerous entity types, which are distinguished by keyword qualifiers and context.
 An entity string value may variously consist of plain text, SGML tags, and/or references to previously-defined entities.
 Certain entity types may also invoke external documents.
 Entities are called by reference.