Good idea to document this. I approve! Review of the candidate manpage follows:

> I'm wondering whether the `SYNOPSIS` is too busy.
>
> Perhaps it would be better as just this:
> ```
>
> ```
>
> That says you the command has one optional argument, _field_, and that's basically all that it needs to say.
>
> I guess the `DESCRIPTION` should then be:
> ```
> This command provides a way to retrieve information about how Tcl was built.
> Without a the command returns the Tcl patchlevel, followed
> by the followed by the fossil commit-id followed by a list of
> dot-separated tags. If a is given, this command extracts that
> field as described below. For official Tcl releases, the are:
> ```
>
> The remaining parts of the manual page look fine. Perhaps we ought to add more references into the `SEE ALSO` section? (`platform(n)` and `tcl_platform(n)`/`tclvars(n)` would be my candidates.)
>
> If you don't change the `SYNOPSIS` as suggested, at least remove the `?` from the first line of it; the subsequent lines make it unnecessary in that case and it's technically ambiguous according to our simple command syntax rules.

Do as you will with the review, but I hope it helps.