I'd quote mine, but its all butchered so... Essentially it depends on the spellcast itself. Mine, before I edited it, was like such: Normal gear sets = Idle/TP, but casting Poison V (just type /ma "poison V" <t>/<me>) would toggle Idle/TP to PDT set, and casting it again would rotate to MDT set, then once more would put me back in normal Idle/TP sets.
The aforementioned can be used to set things like like Low/Mid/High-Acc TP situations, Low/Mid/High-Acc WS Situations, Low/Mid/High DEX situations.
The other type you seem kind of familiar'd with but:
Code
<elseif spell="Shining Fantasia">
<cancelspell />
<if advanced='"$DDRing"="Tyrant's Ring"'>
<var cmd="set DDRing Mars's Ring" />
</if>
<elseif advanced='"$DDRing"="Mars's Ring"'>
<var cmd="set DDRing Tyrant's Ring" />
</elseif>
<addtochat color="135">DD Ring: $DDRing</addtochat>
<command>Dancing Chains</command>
</elseif>
Toggles my TP ring between Mars's and Tyrant's if I cast Shining Fantasia. Things like that can be used for simple gear swaps, TP -> PDT, TP -> MDT, TP -> PDT/TP Hybrid etc. The spell just depends on which spell is there in the code. I would use actual spells, that can't be used on the job you're on, but you can always experiment.