Nothing on neither AA's nor SQ's site to confirm this, and it does seem indeed odd. Nothing to do with JL either.
The official website for Changi International Airport (http://www.changiairport.com.sg) shows that AA is codesharing on SQ flights from three destinations:
(they exclude FRA, so not sure if it applies to stopover rights, assuming it exists)
(this is via NRT, not the nonstop)
(same situation with the ICN stopover being excluded)
....neither LAX's website nor AA's website recognizes these flight numbers, but they're plainly there on Changi's. That, and some Singaporeans on the Airwise forums have been talking about it for a while.
What's up with this??
[Edited 2004-11-23 21:13:13]