The bridge is called "Ghodi" (Ghoda means horse).
The act of filing the "Ghodi" is a part of the "Jawari" optimization process.
"Khulla" means open. Hence the timbre of the instrument is vibrant, bright and resonant. The string has a raised front half to create this tone.
"Bandha" means closed. Jawari gurus will usually lay the string with full contact with the bone surface to produce this type of tone. It has a dull sound but produces more sustain and triggers the sympathetic string more effectively
The above was excerpted from Raganet Issue #1
The videos below demonstrate the different tonalities achieved by the differing approaches to the jawari optimization process.
Vilayat Khan used a closed jawari.