Files with the .X_T extension contain information concerning 3D CAD models – their geometry, topology, and color, written in text format. This type of encoding ensures easy importing of the file across a range of CAD modelling applications. The same data, written in binary form, is contained in .X_B files.

The X_T file extension is unique to the Parasolid software, an app for geometric CAD modelling, and specifically its Standard, Translators, and Bodyshop editions. It is used for exporting models for the purposes of further file sharing. It has replaced older formats, namely XMT_TXT and XMP_TXT.