Weird Buttons Below Channels' Buttons

[Really Weird Person]

What do the buttons below the channels' buttons do? What I mean is the ones with the centered underscore-like characters on them. It would be something like this

Button: Channel something (mutable and unmutable)
Button: Centered underscore (seemingly does nothing when pressed)

Edit by mod: Is it really necessary to write one thing 128 times and change its number? Therefore removed 127 of them.

[SoundCrafter]

OK, that many was completely unnecessary. A simple etc. would've worked.  
Those buttons allow you to access the effect of a channel if you've put one on that channel. The 'centered underscore' would be replaced by the effect's name.  

[LPChip]

Agree with SC, and therefor modified the post.

As SC pointed out, when you load a VST plugin, and assign it to a channel, the first instance will be placed in the [     ---       ] slot of that channel. This way, you can quickly edit its settings. If you want the second plugin, you click that button, and then go to the menu Info->Outputs->... which has a list of the next plugins in the chain.