The 1SV277 is documented in this 71.9 KB PDF, which the catalogue lists as a schematic. Its 1SV prefix indicates a varactor diode, so the content is most likely a component datasheet. Technicians open such files in a standard PDF viewer to look up capacitance at specific bias voltages, check the reverse voltage rating and confirm package dimensions and marking. Compare those details with the diode fitted on the board before relying on any substitute in an RF or tuning stage.
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.