+Z:be perpendicular to the sample surface,directs to the out-side
+Y:be perpendicular to the fluorescent tube,directs to the PCB surface
+X:be parallel to one side of the PCB surface,directs to the right
其中,英文文献中也有在"direct"处用"point"表述的.
此外,如果PCB板有多个侧面或两侧夹角非零,请标明；若PCB只有平行侧面,请去掉+X中“一侧”的说法.
供你参考