Series/ Parallel pickup wiring?

[jazzyvee]

I've just been reading a thread on another bass forum about Alembic Elan basses.
https://www.talkbass.com/threads/alembic-elan.735640/

In one comment where the writer had a 6 string élan plus he states that the plus option was a series/parallel switch.
I've never heard of that option on an alembic before so that got me thinking what is the standard configuration for pickup wiring in alembics, series or parallel, how does that work with single or dual pre-amp basses or guitars and what is the difference sonically of each method?

[mica]

Elan plus is simply the addition of bass and treble cut flat boost switches to a standard Elan. You can think of it as Europa with a face-mounted jack.

[mica]

Our systems are wired in parallel. The hookup wire is single conductor shielded wire. If you were to wire in series, you would get hum something fierce. That also means that things like coil tapping don't apply either.