Hitachi ZX 38U-5A Technical Manual page 42

SAFETY
Never Ride Attachment
 Never allow anyone to ride attachments or the load. This is
an extremely dangerous practice.
Precautions for Communication Terminal
Electrical wave transmitted from the communication terminal
may cause malfunction of other electronic devices.
Inquire the device manufacturer for electrical wave
disturbance upon using an electronic device near the
communication terminal.
SA-36