sqlite> select false is true < false;
1
sqlite> select sqlite_version();
3.32.3

vs.

PostgreSQL> select false is true < false;
false

PostgreSQL> select version();
PostgreSQL 9.6.17 on x86_64-pc-linux-gnu (Debian 9.6.17-2.pgdg90+1), compiled by gcc (Debian 6.3.0-18+deb9u1) 6.3.0 20170516, 64-bit

Other SQLs also seem to treat IS TRUE (and IS FALSE) as a two-word operator not a modified IS.

This began as an issue with the documents here but I believe there are actual bugs so I started a separate thread to discuss correctness.