If all exchanges have invented a liquidity-field, then there's a good chance the next version of FIX will standardize it, no?
Imho the legal system is very much ripe for digitalization. Both on the low-end (where it pretty much consists of overhead), and even more so on the high-end, where the complexity of legal contracts between companies or states has long exceeded what any team of lawyers (much less a mere mortal) can comprehend.