Enabling push-pull operations?

[SymphonicPoet]

I've got several large stub end stations, some sizable commuter networks, and even some oddball freight mods I've put together, and it'd be nice to have trains backing up into things at least part of the time. (Honestly, I'd love to eliminate the "NIMBY bounce" from my system completely.) But lord if I can figure out how to make the push-pull tag work. I use a completely custom set of trains. I don't see where to put it in the mod. I can't figure out how the AI applies the "push-pull" tag in-game.

The guide says you need a locomotive or control car at each end. How does the game know what is or isn't a control car? I'd have guessed it was power, but all my freight cars have a small amount of fictional power so that they'll spawn correctly when I set a string of them on a siding for decoration. (It does mean they roll back and forth sometimes, but . . . meh . . . I can live with that. You don't usually notice it unless you're focusing on a yard. The freight trains are really just there as decoration, and to complicate passenger operations anyway.)

So long story short, what am I missing? I want to use push-pull, but I don't understand it.

[TKR]

either you give the TrainMultipleUnit the 'push-pull' or 'mu' tag, or you make sure the first and last car of the train have the 'locomotive' or 'control' tag.

[SymphonicPoet]

I think I'm not seeing how you write that tag into a mod; where in the mod it's supposed to go. That's not something that's clear to me from the mod guide, and I'm not using anything but custom mods, most of which I wrote myself, and they all predate both coupling and push-pull. I need to make old mods work with current features. Will keep looking. Maybe it's just a string of text in the mod with hyphens? Maybe at the end of each TrainUnit block?

[Harbie]

As TKR mentioned, if for example you use the 'mu' tag, it goes in the [TrainMultipleUnit] section as
tags=commuter,regional,standard,electric,mu

[adlet]

I have been using push-pull - does "mu" tag have any difference?

To OP, the front/end car does not necessarily have power. Front/end cars of many multiple unit trains have controls but not power.

[TKR]

so far push-pull and mu have the same effects. Perhaps in the future a feature may be added that changes this.

[SymphonicPoet]

Aha!
[TrainMultipleUnit]
. . .
tags=thing1,thing2,thing3 . . .

That's what I needed. If it's in the mod guide I didn't see it. Thank you!