Can I ask why you are trying this in RNAV, GPS, or RNP ?
What I have designed is a single RNP or RNAV procedure that will work for a multi-variant platforms, rather than a specific procedure for each aircraft class/type. This way, ATC only has to know one set of waypoints, rather than multiple sets.
As an example, with a turn to final, one procedure would make everyone drive the A380/747 track, so the 737 drivers would fall asleep on final.
With the offsets, the A380 can offset to the outside, while the 737 can offset to the inside. The offsets can be set to release at the FAF for the straight in, but the box I was working with, the HW, automatically removed the offset when encountering a FAF waypoint.
As noted, this worked with my test platform and flight val.
I have an airline with the 777 platform, with a Smiths box, and does not allow for anything less than whole nm offests...(than I can figure out)
Honeywell FMZ and Collins GNLU 910 will accept decimal offsets.
Thanks Hop for the information...