Chicago O'Hare used to have a MLS approach. I have seen the approach plate for it, but the approach (and the accompanying approach plate) has been deleted.
MLS was supposed to replace ILS, the capabilities of MLS over ILS were a 3D approach allowing multiple categories of aircraft to conduct the approach over different flight paths, versus the single straight in. It would also allow aircraft different glidepaths as well. MLS also included a data link which would give incoming aircraft runway status, weather, etc.
Development of MLS was further along in Europe than in the US. The FAA decided to abandon development of MLS after GPS arrived on scene, so MLS what few MLS approaches there are will be gone by 2010.
There is more info in the AIM. http://www1.faa.gov/atpubs/AIM/Chap1/aim0101.html#1-1-11
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