As per the recent Enum spec (Preliminary Proposed Final Draft 2)
Section III:- Semantics
It is mentioned that:-

It is illegal to reference a non-constant static field of enum type from its constructors, instance initializer blocks, or instance variable initializer expressions.

With respect to Tiger-beta2 build 44 tested on Solaris-9 only:-

The behavior is:-
1) One can not refer any static or constant static filed of any type from constructor. Compile time error

2) One can refer any static or constant static field of any type from instance initializer. No compile time error in this case, but fails at runtime.

How to reproduce:-
Execute the code mentioned below:-
import java.util.*;

enum Students {
  GRAD,
  PhD;
  
  Students() {
     System.out.println("Const is being called");
     System.out.println("Const the enum constant is :"+this.toString());
     
     //System.out.println("The value of k is :"+k);
     //System.out.println("The value of i is :"+i);
     // System.out.println("The value of h is :"+h);
     //studentsMap.put(toString(), this);
     
     
  }
  
   static final Map<String, Students> studentsMap = new HashMap<String, Students>();
   static int k = 100;
   final static int h = 500;
   final static Integer i =678;
   
   
    { // simple instance initializer block
      System.out.println("Initializer block is being called");
      
      System.out.println("The value of k is :"+k);
      System.out.println("The value of i is :"+i);
      System.out.println("The value of h is :"+h);
      System.out.println("Intializer block the enum constant is :"+this.toString());
      System.out.println("The value of studentsMap is :"+studentsMap);
      studentsMap.put(toString(), this);
      
    }
}


public class GeneralTest4 {
   
   public void assertion1() {
        Students enum_ref = Enum.valueOf(Students.class,"GRAD");
   }
   
   public static void main(String args[]) {
       GeneralTest4 ref = new GeneralTest4();
       ref.assertion1();
   }

}

Output got while executing:-
Initializer block is being called
The value of k is :0
The value of i is :null
The value of h is :500
Intializer block the enum constant is :GRAD
The value of studentsMap is :null
Exception in thread "main" java.lang.ExceptionInInitializerError
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:495)
        at java.lang.Class.getEnumConstants(Class.java:2510)
        at java.lang.Class.enumConstantDirectory(Class.java:2531)
        at java.lang.Enum.valueOf(Enum.java:186)
        at GeneralTest4.assertion1(GeneralTest4.java:42)
        at GeneralTest4.main(GeneralTest4.java:47)
Caused by: java.lang.NullPointerException
        at Students.<init>(GeneralTest4.java:33)
        at Students.<clinit>(GeneralTest4.java:4)
        ... 9 more

Expected Output:- Should not compile