The mysterious constant pool tag #2

x4e_x4e x4e_x4e at
Wed Jan 13 19:28:41 UTC 2021


I am attempting to find the purpose of the seemingly abandoned constant pool tag number 2.
My guess is that the item type denoted by this tag was removed and the tag was never reclaimed.

I've attempted to locate the earliest possible JVM spec including this constant tag - to no avail.
The earliest spec listed on is the SE 6 spec, which does not include the tag.
I did however find the original JSR catalog (, however it is unclear which JSR contains the first JVM specification (Many links 404 and earlier specifications only cover the language side of things).
As far as I can tell, this is the first final release JVM specification: however, once again, it seems that there is no constant tag number 2.

I am wondering if anyone here (probably someone involved in the early JVM design) knows the original purpose of tag number 2?

Thank You.

PS: I found that you can actually buy the original JVM specification on amazon ( - even new!


More information about the jdk-dev mailing list