HP Color LaserJet 5500 Technical Reference Manual page 45

Although printers supporting context switching can select
printer languages accurately, we recommend that every job
containing printable data include an ENTER LANGUAGE
command to explicitly select the correct printer language.
This method improves performance and eliminates
unintentional printer language switching, which can
potentially cause data loss. Performance is not adversely
affected if both the application and the spooler send the
ENTER LANGUAGE command.
Figure 4-1. Switching Printer Languages
Kernel Commands 4-9