Boardview archive for a board labelled ZH6-PB, where PB likely marks a sub-board such as a power or port board, though the name does not name the device or brand. The 86.1 KB RAR should contain a layout file viewable in OpenBoardView, FlexBV or a similar boardview program. It lets a technician locate parts, test points and nets on the physical PCB while measuring a short or missing voltage. Compare the board code printed on the PCB with ZH6-PB before trusting the part placement.
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 .rar file
Compressed archive — the usual wrapper for a schematic + boardview pair or a BIOS + EC set.