ASUS X421EAY motherboard boardview with board number 60NB0RL0-MB5511; no revision is stated in the name. The .brd shows where each component sits and which net it joins, so a technician can find coils, capacitors and MOSFETs on a faulty rail, pick test points and inspect both sides of the board. Viewers such as OpenBoardView or FlexBV open it. ASUS issues several MB codes under one 60NB0RL0 base for different CPU and memory builds, so match the full number on the PCB sticker before using it.
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 @boardviews_schematics. Enginerys does not host this file.
How to open a .brd file
The most common boardview extension. Several unrelated formats share it, which is why one viewer opens a .brd and another refuses it.