[Fontforge-users] How to implement OpenType blwf feature

[Smith R. <ma...@gm...>]

I am trying to implement the 'blwf' feature (as mentioned here: 
http://www.microsoft.com/typography/otfntdev/Teluguot/features.aspx) in 
the Telugu Indic script. It involves a [Consonant+Halant], which will 
both be replaced with a below base mark of the consonant type. I was 
wondering as to how I should achieve this with Fontforge?

I have tried to do the same thing as 'abvs' substitution, but the Halant 
stays there.

Regards.