File with a .BLK extension contains highlighted elements of a drawing and its properties of the AutoCAD project. It is the so-called template for attributes extraction and it is used to publicise projects in DWF, DWFX or PDF formats.

BLK files can be created within the attributes downloading wizard of the AutoCAD software or via dialogue window of a Block template. Utilising it, the author can decide which of contained data are to be displayed in generated and shared view files.