T he Analytical Information Markup Language (AnIML) is a standardization effort of ASTM (formerly American Society for Testing and Materials) Subcommittee E13.15 on Analytical Data. AnIML provides an XML-based format for analytical data. It is designed specifically for spectroscopy and chromatography data, but is suitable for use with many different analytical measurement techniques. AnIML consists of a generic core structure that permits the storage of arbitrary analytical data. These include multi-dimensional data, name-value pairs, and hierarchies. The concept of technique definitions permits the formal specification of constraints for usage of the core. This way, a definition can prescribe how the data for specific measurement techniques should be captured in the data file. To address changing requirements, AnIML supports an extension concept that allows vendors or end users to specify additional data that should be stored for a technique. These extensions can also be formally documented so that they do not break compatibility with existing software. This article presents an overview of AnIML and demonstrates how AnIML can be used to record data from everyday experimental workflows in a laboratory environment. Issues related to the usage of AnIML in regulated environments are also discussed, including the use of digital signatures and audit trail functionality to ensure data integrity. ( JALA 2004;9:375-81) This project is funded (in part) by NIST's Systems Integration for Manufacturing Applications (SIMA) Program.