Filed as a schematic, 1SV231 is a 68.1 KB PDF named after a component code; the trailing underscore is not part of it. The name ties it to no specific equipment or board. The 1SV designation is commonly used for variable capacitance diodes, so expect polarity marking, the package drawing and capacitance-versus-bias curves. This information helps when testing a diode in an RF tuning stage or when matching a substitute by capacitance ratio and package. Verify the marking on the fitted part first.
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.