I think you're thinking of index stream readers?

I have heard of neither. But the mention of Burrows leads me to Burrows-Wheeler, which is a compression algorithm (bzip).

I'm not 100% but I don't think you can directly query a BWT in the same way you'd query an inverted index (without the later discovery of wavelet trees and FM-indexes / succinct data structures, and all that jazz.) And that's mostly for genomics? Not sure if it applies to plain old document searches. Would love to be corrected though.