Y-Split

[7447C_Twisted_Wire]

<R12> A maximum of one (1) VEX Y-cable can be used per Motor Port of the Microcontroller or
Power Expander. (You cannot “Y off a Y” to have more than two (2) motors controlled by the same
Motor Port.)

It would be illegal if I plugged a y-split into a power expander, and y-split from its output, right?

[AidenPyle]

<R12> A maximum of one (1) VEX Y-cable can be used per Motor Port of the Microcontroller or Power Expander. (You cannot “Y off a Y” to have more than two (2) motors controlled by the same Motor Port.) a. Teams using the VEX ARM® Cortex®-based Microcontroller can only power one (1) 2-wire Motor per each of the two 2-wire motor ports on the Microcontroller. It is illegal to “Y” off a 2-wire Motor Port.
b. Teams may not “Y” off a Motor Controller 29

You are allowed to plug a y-cable into a power expander, but you can’t “Y off a Y”.

[puzzler7]

@7447C Twisted Wire

It would be illegal if I plugged a y-split into a power expander, and y-split from its output, right?

No, that is legal (or was legal in Starstruck). See this Q&A.

This is probably something I should know by now, but how do old Q&A rulings that still apply to current games work? Is it safe to assume that they are still correct interpretations of the rules unless otherwise specified?

[Mango]

You can, just as long as you end up with 12 or fewer motors, and don’t continuously Y split off of other Y splits to create more ports.

[sankeydd]

@puzzler7

No, that is legal (or was legal in Starstruck). See this Q&A.

This is probably something I should know by now, but how do old Q&A rulings that still apply to current games work? Is it safe to assume that they are still correct interpretations of the rules unless otherwise specified?

That’s a great question for the official q and a!