Define "XML" and state its role in achieving semantic interoperability in Electronic Health Records (EHRs).

XML, which stands for Extensible Markup Language, is a text-based format that is used to store and transport data. It is both human-readable and machine-readable, making it a versatile tool for data exchange. XML uses tags to define elements and can represent complex hierarchical data structures.

In the context of Electronic Health Records (EHRs), XML plays a crucial role in achieving semantic interoperability. Semantic interoperability refers to the ability of information systems to not only exchange data, but also to interpret and use the data in a meaningful way. This is particularly important in healthcare, where the accurate interpretation of data can have significant implications for patient care.

XML contributes to semantic interoperability in EHRs in several ways:

1. Standardization: XML provides a standard format for data exchange, which helps to ensure that different systems are "speaking the same language". This is particularly important in healthcare, where data may be exchanged between a variety of systems and devices.

2. Flexibility: XML is extensible, meaning that it can be adapted to represent a wide range of data structures. This makes it a versatile tool for representing the complex and varied data found in EHRs.

3. Self-describing: XML data is self-describing, meaning that the structure and meaning of the data is encoded within the data itself. This helps to ensure that the data can be accurately interpreted, even if it is being read by a system that was not involved in its creation.

4. Interoperability: By using XML, EHRs can achieve a high level of interoperability. This means that they can exchange data with other systems, and that this data can be accurately interpreted and used by those systems.

In summary, XML is a powerful tool for achieving semantic interoperability in EHRs, thanks to its standardization, flexibility, self-describing nature, and support for interoperability.