http://postgis.refractions.net/pipermail/postgis-users/2003-June/002651.html * The MySQL code contains an assumption in the WKB handling that all WBK will be little endian. If you run MySQL spatial on a big endian machine (Sparc, PowerPC, PA-RISC) you will find things go amiss when you try to send WKB to little endian machines (x86), because your big endian machine will be creating invalid data (big endian data incorrectly flagged as little endian).
