HA!! Hoist by me own petard... your suggestion indeed worked great, and I though that would be the end of, since I don't write batch files and have no need to do percent-sign conversions...
except that I *do* use that feature - in my PROMPT!!
set prompt=`%@exec[@color 10 on 1 & echos %@lower[%_cwd] & color 13 on 0 & echos Yes, Master?? & color 3 on 0] $g `
So I guess I'll have to stick with the back-quote method, which works fine.
The problem I was trying to solve, and *have* solved, is that I wanted to take links from Google Earth, and paste them into Firefox for display. However, Google Earth renders URLS with special characters encoded as %HH :
If I paste that verbatim into Firefox, it doesn't handle it properly, so I wrote a little C utility that takes the line in, converts it back to normal characters, and I can paste the result into the browser just fine. Since I'm likely the only person who is ever going to use this function, the back-quote solution is not a problem.
Thanks for the great response!