A 50.3 KB datasheet PDF for the 1N748A, part of the JEDEC zener series spanning 1N746A through 1N759A, stored in the schematic section of the index. It covers nominal zener voltage at a stated test current, impedance, reverse leakage and power limits, plus the package outline. The figures help when checking a clamp or reference circuit that measures off, or when sourcing a replacement from another maker. Match the voltage, tolerance and wattage, and fit the part with its cathode band facing the correct way.
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.