An ASV file is a so-called Adobe Selective Color file, so a selective color setting file for the image editing software Photoshop. Asv files contain settings for the CMYK colors Cyan, Magenta, Yellow and Black in a range of -100% - 100%, as well as the application mode (relative or absolute).
Selective colors are used, for example, when repainting color areas of an image. (green house in a red house, black / female image with individual colored objects) ASV files are applied via an adjustment layer, which has to be created via the menu 'Layers->' Adjustment layer-> selective color correction '. After clicking on 'Ok' you can change the values for the individual colors in the 'selective color options' and load and save ASV files.