There are confusing/unclear stories:
One, from the Princeton source you put, and also from MIT archives, states that:
Note: The 1.0 release of the Java language supported five access levels: the four listed above plus private protected. The private protected access level is not supported in versions of Java higher than 1.0; you should no longer be using it in your Java programs.
But this feature is not specified on any official documentation for Java 1.0 here or here.
My guess is that this feature didn't make it to the official 1.0 version, since the official language specification is from August 1996 and Princeton source was last modified on February 1996.
PS: shame on Oracle for removing the archives for older versions.