Recent promoted releases of the reference JDK 1.3 contain correspondent HotSpot
as a default VM. However, the default VM for java_g is classic VM:

>>>> /usr/local/java/jdk1.3/solaris/bin/java -version
java version "1.3.0"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.0-O)
Java HotSpot(TM) Client VM (build 1.3-O, interpreted mode)

>>>> /usr/local/java/jdk1.3/solaris/bin/java_g -version
java version "1.3.0"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.0-O)
Classic VM (build 1.3.0-O, native threads, nojit)

I believe that this is a bug in JDK 1.3 build.