PDF bearing the Texas Instruments literature number SDLS111, a code from the series TI uses for its legacy TTL logic datasheets. At 1.04 MB it is noticeably larger than its neighbours and may cover a device family or include extended application data. The file name does not identify the parts inside, so check the title page. Use the pinouts, function tables and electrical limits to check suspect logic chips on older boards and to confirm that an alternative part matches in levels and timing.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @datasheet_technar_org. Enginerys does not host this file.
How to open a .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.