ISO 14230-2:2016 specifies data link layer services tailored to meet the requirements of UART-based vehicle communication systems on K-Line as specified in ISO 14230‑1. It has been defined in accordance with the diagnostic services established in ISO 14229‑1 and ISO 15031‑5, but is not limited to use with them and is also compatible with most other communication needs for in-vehicle networks. The protocol specifies an unconfirmed communication.

The diagnostic communication over K-Line (DoK-Line) protocol supports the standardized service primitive interface as specified in ISO 14229‑2.

ISO 14230-2:2016 provides the data link layer services to support different application layer implementations like the following:

- enhanced vehicle diagnostics (emissions-related system diagnostics beyond legislated functionality, non-emissions-related system diagnostics);

- emissions-related OBD as specified in ISO 15031, SAE J1979-DA and SAE J2012-DA;

- in addition, ISO 14230-2:2016 clarifies the differences in initialization for K-line protocols defined in ISO 9141 and ISO 14230. This is important since a server supports only one of the protocols mentioned above and the client has to handle the coexistence of all protocols during the protocol determination procedure.