Contexual Alternates

I’m building a brush script font & I have been through this tutorial a couple of times.

https://glyphsapp.com/tutorials/features-part-3-advanced-contextual-alternates

I keep running into issue towards the bottom of the tutorial. I want my letters to have contextual alternates. There is a part of the tutorial where it talks about this…

Con0: B C D
Con1: B.ss01 C.ss01 D.ss01
Con2: B.ss02 C.ss02 D.ss02

Voc0: A E I
Voc1: A.ss01 E.ss01 I.ss01
Voc2: A.ss02 E.ss02 I.ss02

Etc: space comma

Where do I set this up? Do I make a new class called “con” and one called “voc” and one called “etc” ??
Still very new to all of these features and any help would be greatly appreciated!
I could do everything up until that point, and it worked properly.

Yes, as described in that very tutorial you mention. Which part was unclear? Perhaps I can improve the wording.

@mekkablue I just don’t understand how to get from here:

to here:

and I keep getting an error message that looks like this:

but i’m not sure why. Obviously i’m doing something wrong, I just don’t know what. Please help and thanks!

Read the error message: you are replacing a class with another. And they do not have the same number of glyphs in them.

You do not know how to add classes? It is described in detail in part 2 of the tutorial series:

… click on the Plus button and create a class definition. You can rename it by double clicking on the xxxx, just like you would rename a feature tag. A class name must start with a letter from A-Z or a-z, and can also contain underscore, period and figures.

Or in the handbook, in the Font Info chapter, section 7.4, starting on page 93.