Två centrala begrepp i metamodellen är Funktion och Förmåga. För att förenkla för läsaren görs här en genomgång på dessa begrepp. Framförallt är det ordet Förmåga som har många olika betydelser i engelskan såsom "Business Skill", "Capability", "Ability", m. fl. Även när ord används i kombination ändras betydelsen. TOGAF referera till "Business Capability" som "Function" och skiljer därmed på "Capability" och "Business Capability".
*_TOGAF9 defines a Function as:_*
_Function describes units of business capability at all levels of granularity._
_The term "function" is used to describe a unit of business capability at all levels of granularity, encapsulating terms such as value chain, process area, capability, business function, etc._ 
_Any bounded unit of business function should be described as a function._
_\[a Function\] Delivers business capabilities closely aligned to an organization, but not necessarily explicitly governed by the organization. Also referred to as "business function"._
*_TOGAF9 defines a Capability as:_*
_A business-focused outcome that is delivered by the completion of one or more work packages._ 
_Using a capability-based planning approach, change activities can be sequenced and grouped in order to provide continuous and incremental business value._
I svenskan har begreppet förmåga har en tvetydig användning som ibland kan ses som funktion och ibland som förmåga. I version 3 av ArchiMate finns stöd för att använda både funktion (Business Function) och förmåga (Capability). I metamodellen lutar vi oss på ArchiMates definition.
*_ArchiMate v3 defines a Capability as:_*
_\[A capability represents an ability that an active structure element, such as an organization, person, or system, possesses.\]_
_In the field of business, strategic thinking and planning delivers strategies and high-level goals that are often not directly implementable in the architecture of an organization. These long-term or generic plans need to be specified and made actionable in a way that both business leaders and Enterprise Architects can relate to and at a relatively high abstraction level._
_Capabilities help to reduce this gap by focusing on business outcomes. On the one hand, they provide a high-level view of the current and desired abilities of an organization, in relation to its strategy and its environment. On the other hand, they are realized by various elements (people, processes, systems, and so on) that can be described, designed, and implemented using Enterprise Architecture approaches. Capabilities may also have serving relationships; for example, to denote that one capability contributes to another._
_Capabilities are expressed in general and high-level terms and are typically realized by a combination of organization, people, processes, information, and technology. For example, marketing, customer contact, or outbound telemarketing \[4\]._
_Capabilities are typically aimed at achieving some goal or delivering value by realizing an outcome. Capabilities are themselves realized by core elements. To denote that a set of core elements together realizes a capability, grouping can be used._
_Capabilities are often used for capability-based planning, to describe their evolution over time. To model such so-called capability increments, the specialization relationship can be used to denote that a certain capability increment is a specific version of that capability. Aggregating those increments and the core elements that realize them in plateaus (see Section 13.2.4) can be used to model the evolution of the capabilities._
*_ArchiMate v3 defines a Business Function as:_*
_\[A business function is a collection of business behavior based on a chosen set of criteria (typically required business resources and/or competences), closely aligned to an organization, but not necessarily explicitly governed by the organization.\]_
_Just like a business process, a business function also describes internal behavior performed by a business role. However, while a business process groups behavior based on a sequence or flow of activities that is needed to realize a product or service, a business function typically groups behavior based on required business resources, skills, competences, knowledge, etc._
_There is a potential many-to-many relation between business processes and business functions. Complex processes in general involve activities that offer various functions. In this sense a business process forms a string of business functions. In general, a business function delivers added value from a business point of view. Organizational units or applications may coincide with business functions due to their specific grouping of business activities._
_A business function may be triggered by, or trigger, any other business behavior element (business event, business process, business function, or business interaction). A business function may access business objects. A business function may realize one or more business services and may be served by business, application, or technology services. A business role may be assigned to a business function. The name of a business function should clearly indicate a well-defined behavior. Examples are customer management, claims administration, member services, recycling, or payment processing._