Paladin Seal macro - help!

Anyone know if there is a way to conditionally switch to a different paladin seal via a macro?

For druids, for example, you can do something like this:

/cast [nostance:5]Moonkin Form; Wrath

That would throw you into moonkin form if you aren't in it and cast Wrath if you are in moonkin.

I'm trying to figure out something like that for seals if such a thing exists, but haven't been able to find it. Seals aren't buffs, strictly speaking, any more, nor do they seem to be auras or anything else obvious.

Ideally I would use this macro as a preface to handle different types of fights - have it put on seal of truth if I'm spamming my single-target key, seal of righteousness if I'm doing AOE, and seal of insight if I'm casting spells.

You can use null to keep it from overcasting and either add it as a step or add it as a"leader" castsequence for another ability

Code:

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/castsequence reset=combat !Seal of Righteousness, null
/cast Divine Storm

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Code:

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/castsequence reset=combat !Seal of Truth, null
/cast Crusader Strike

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That second bit is what I wound up doing - also, you don't need the ! before the name since it doesn't seem to cancel it, and will re-cast it even if you have it on already. Basically I was just hoping for a way to avoid wasting mana.

Thanks for the help!