PES E does not have to go back for reservist, I dun know
official or not, but that is the case. How I know because of my
diabetes, I went back recently for my ICT and the MO told me, its
either PES C9 L3 or PES E, he says the difference is PES C I need
to come back, PES E dun need. In the end, medical board put me as
PES C9 L3 so still got to go back for ICT probably doing admin work
in HQ COY. But its true you still got to inform them when you go
overseas. Its not anything to do with PES status but its an issue
for them in terms of resource deployment in case there is a need to
deploy people.
No reservist for PES E, but they are required to report for duty
during times of war or crisis. To remain contactable if called by
Mindef. Was in some Mindef guideline I think.