‘Canonicity’: the Book or the Reader?

[Maédhros]

The question of Canon is a common concern that we have to deal with in the Revised Silmarillion Project.
I have seen many good ideas in this thread but unfortunately, it really doesn't help a casual reader to regard the validity of each text, typescprit, manuscript, published text, letters, etc.

We have developed some practical rules that guide us in our work. I thought that I would post some of them in here:

1. The first priority is always given to the latest editions of works published during Tolkien's lifetime.

2. Secondary priority is given to the latest ideas found among Tolkien's unpublished texts and letters, except where they:
a. violate the published canon without specifically correcting an error or
b. are proposed changes that do not clearly indicate the exact details that must be changed and how they are to be changed.

5. Information in sources of lower level priority is to be preferred over information in sources of higher level priority where the item of information in source of higher level priority can be reasonably demonstrated to be an error, whether a "slip of the pen" or from inadequate checking of previous writing.