Symbol 5388 from IEC 60417 - Title/Meaning: Beam limiting device with separate closing of the shutters Function/description: To identify controls for closing one set of shutters or a single shutter of a beam limiting device.
Additional information: 
The controlled shutters are shown in thicker lines
Published in: Supplement G, 1985
Own work using: iso.org/obp/graphics/grs/f30c3f5d-535e-460a-baae-8baca0e50168 200.png
Vectorization:  Mrmw