Microsoft proposes a partial typology of Windows Local Accounts in Microsoft, 2019(1) :

The attentive reader will observe the absence of a description for the Non-Default Local System Account. But before getting into that, the first step in analyzing this partial typology is to define its dimensions.

Default vs. Non-Default

Default vs Non-Default: Per Microsoft, 2019(1), default accounts are built-in accounts created automatically when the OS is installed. Conversely, non-default accounts are non-built-in accounts created after OS installation.

Built-in is an ambiguous term (Built-in (Dictionary Entry)). In effect, the term designates an object that is related to another object for several distinct reasons, e.g. because:

• it forms an integral part of it,

• it is included, made or designed as part of it,

• it was included in it when it was created,

• it is permanently connected to it and cannot be easily removed.

These ambiguities do not allow to classify entities in some grey areas, such as:

• when an account that is an integral part of the OS is deployed by Microsoft after OS installation as part of an upgrade,

• when an account that is an integral part of the OS is deployed as part of the installation of a complementary Windows Component after OS installation,

• when an account that is an integral part of the OS is deployed by a third party (e.g.: a device driver, that is defined as a trusted part of the OS that can execute within it with System account credentials, Russinovich et al., 2017),

• when a custom account is created as part of a custom script during OS installation.

Nevertheless, arbitrages can be made to classify accounts in these grey areas. In consequence, for operational purposes, we may state that the default vs non-default dimension satisfies in general the properties of exhaustivity and mutual exclusivity. That is to say, a Windows Local Account is either an integral part of the OS or it doesn’t and the default vs non-default dimension may be considered an unidimensional typology (cf. Bailey, 1994, p.3).

System vs. Non-System

System vs Non-System: System accounts are used by the OS and its services.

To privilege concision and readability, definitions are provided via dictionary entries under the References column.