File format used to store X-ray powder diffraction measurement data collected by PANalytical XRD instruments such as Data Collector and X'Pert Powder; also contains any information required to reproduce the measurement data, which includes the instrument type and settings.

XRD data was originally stored in binary format to save space but did not allow easy analysis of the data. The XRDML format was eventually introduced, enabling users to more conveniently access and share their measurement results. The XRDML file is an XML based file that contains XRD measurement data in ASCII format. Powder diffraction is an analytical scientific technique used to identify the phase of a crystalline material. It can also reveal information about unit cell dimensions.