What a stupid document that is, TEEEJ. It doesn't even explain the difference between 'recall' and 'call-out' - which is very significant indeed.
When I was doing PVR-porridge at Binnsworth, I looked into the whole thing because I was tasked to investigate why reservists weren't responding to their invitations to join Bliar's illegal Iraqi adventure. The reason was blindingly obvious - utter institutional incompetence. PMC had failed to establish a robust system for tracking non-pensionable peoples' changes of address after leaving the mob and had seemingly forgotten that some of the single females might well have changed their names in the years after leaving.
I told the people at Binnsworth that they would have to prove deliberate evasion if they wished to attempt prosecution and would be dragged through the courts by any half-competent brief unless their evidence was cast-iron. The best day was when they'd collected up their 'evidence' - but then I noticed that they hadn't actually copied the notices they'd signed and stamped, just the drafts which anyone could have typed at any time. Neither had they any proof of delivery or even proof of postage - so the evidence was quite useless. Their definition of a Notice having been deemed to be Served was laughable. What utter incompetent idiots - the whole reservist section was looked after by dear old ladies who really weren't up to it.
Anyway, if you want to avoid being dragged back to play in the sandpit, just do some Googling and you'll easily find the relevant legislation governing exemptions.
Or just fail the medical.....