MS VOLT Tutorial

[algrass]

I have two questions:

1- What is the point of defining groups of glyphs as marks if one has already created combined glyphs? In other words: I am trying to add a GSUB lookup table to a Latin font which has already combined glyphs. Can I ignore this step?
2- I tried to create a substitution lookup table but it did not work. I expect there is a syntax issue in my writing of the definitions. But, should I use the glyph ID or the Uni codepoint? Can you provide an example?

Thanks for your help.

[algrass]

I found one answer to question 2: I must use the glyph index as defined in the previous step when importing the Postscript Names.