Prizm Viewer can help you to open only DOC, DOCX, XLS, XLSX, PPT, PPTX, RTF, CSV, PDF, ODT, ODS, ODP, HTML, SVG, DCM, TXT, EML, MSG, DGN, DWG, DXF, TIFF, JPG, JPEG, JP2, JPEG2000, GIF, PNG, RAS, CAL, MIL, DIB, BMP, PSD, PCT, PCX, DCX, PCD, WMF, EMF and TGA files. In order to open the LST document/image, I suggest you use Notepad, or Microsoft WordPad that comes bundled with Windows OS.