:eval yes use and documentation

[Charles Millar <millarc@verizon.net>]

Org mode version 9.5.1 (release_9.5.1-279-g8908fb @ 
/usr/local/share/org-mode/lisp/)
GNU Emacs 28.0.50 (build 344, x86_64-pc-linux-gnu, GTK+ Version 3.24.23, 
cairo version 1.16.0) of 2020-12-31

Here is a use case.

I have many files each with as many as 60 tables that are generated 
using ob -rec. So that the tables are not evaluated during export it is 
convenient for me to set a buffer wide

#+PROPERTY: header-args :eval never-export.

On other hand, each file may also include, under a sub-tree latex source 
code blocks for signature lines, letter heads, etc.

In another sub-tree, called correspondence, those source code blocks are 
called using :noweb yes, such as

   #+begin_src latex :noweb yes
   <<SomeLetterHead>>
   #+end_src

\begin{center}
\today
\end{center}

[Body of letter]

   #+begin_src latex :noweb yes
   <<SignatureLine>>
   #+end_src

If I include in the correspondence sub-tree
:PROPERTIES:
:header-args: :eval yes
:END:

the results are a complete letter, i.e. letterhead followed by the body 
and then signature line.

If I do not include the ":eval yes" property in the sub-tree, only the 
body of the letter results, as expected.

So after all that, here are some questions:

Is ":eval yes" officially allowed and, if so, why is it not documented?

Should it be?

May its use be inferred from other examples such as those from :cache or 
colnames?

I found the following discussion, but it is fairly old:

https://emacs.stackexchange.com/questions/2945/org-babel-eval-with-no-confirmation-is-explicit-eval-yes

Charlie Millar