[NTG-context] Overriding / redefining / disabling standard commands

[Rik Kabel]

List,

What is the preferred way to override a standard command?

My use case is that I am trying to produce html (and epub, but that has 
a long long way to go) from the same source I use for pdf. Some features 
are not needed, and I have separate environment files for each output 
format to accommodate the differences.

I would like to override the standard \index command in one of those 
environment files, eliminating the generation of index references. There 
may be other constructs as well that would benefit from this 
simplification while allowing a common content source file.

On a related note, does anyone have a css file that handles block 
quotations, margin notes, and cross references? I would love to steal 
bits of it.

-- 
Rik