Run the jdk installer as follows:
jdk.exe /s INSTALLDIRPUBJRE=C:\test\JRE

Expected behaviour: JRE should be installed in specified location and JDK/JAVADB should be installed in default location.

Actual behaviour: JDK/JRE/JAVADB are getting installed in default location.

Tested on XP(32-bit) and Vista (32-bit) with 6u21b06/6u19/6u15.

When run as follows:
jdk.exe /s INSTALLDIR=C:\test\JDK /INSTALLDIRPUBJRE=C:\test\JRE,it runs as expected and JDK/JRE are installed in specified locations. JAVADB is installed in default location.