At 82.2 KB, the 1SV228 PDF is the largest of this group and is indexed as a schematic. The underscore after the code seems to be just part of the file naming. No device, brand or board number is stated. The 1SV prefix is commonly used for varactor diodes, so expect reference data covering package, polarity and capacitance against reverse voltage. Technicians rely on such sheets to verify a diode in an RF tuning section and to match replacements by package and characteristics.
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 @cyberlanelectonik. 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.