XML and JSON are commonly used data exchange formats that are widely in use in wireless networking environments. The verbose and redundant nature of XML documents incurs huge transportation overheads in data communications. JSON is a data format that reduces the document size; but its scope is confined to text and numeric data. Also due to the reasons such as lack of schema and limited interoperability features, JSON is more suitable for web based applications, compared to wireless or mobile environments. Since the literature reports serious concerns about the performance of existing data exchange formats in resource constraint networks, there is scope for a lightweight data exchange mechanism. This paper introduces a new lightweight, schema aware data exchange format for data representation and interchange. The proposed format, called LXML, is schema aware and non-binary format based on the XML standards and has the potential to be an alternative format for XML and JSON in a wireless environment. Experimental findings indicate that LXML is a less verbose and efficient data exchange format and its performance is found to be better than the existing non binary data exchange formats.