At least as far back as Python 3.1, the description for Template strings (section 6.1.5 in version 3.6.4rc1 docs) starts by differentiating what Template strings do, as:

Instead of the normal %-based substitutions, Templates support $-based substitutions, using the following rules:

Since this immediately follows a section describing the "Custom String Formatting" and the "Format Specification Mini-Language", which does a type of substitutions that is {} based, rather than % based, it is hard to grasp exactly why %-based substitutions would be considered "normal". Of course, I know why, due to the % operator, but for someone just reading through chapter 6, it is a reference that raises the mental question "Huh? What is normal %-based substitution? Are Templates abnormal, if %-based substitutions are normal? What did I miss? The previous section was about {}-based substitutions? Are they abnormal, too? What are normal %-based substitutions, anyway?" rather than helping to describe what Templates are and do.

We can remove the word "normal" but otherwise the docs read fairly well.

FWIW, when there docs were written, the {} new-style string formatting didn't exist, so the wording was reasonable at the time.

On Dec 10, 2017, at 14:36, Raymond Hettinger <report@bugs.python.org> wrote:
> 
> Raymond Hettinger <raymond.hettinger@gmail.com> added the comment:
> 
> We can remove the word "normal" but otherwise the docs read fairly well.

+1

> FWIW, when there docs were written, the {} new-style string formatting didn't exist, so the wording was reasonable at the time.

Exactly.

FWIW, this was already fixed in the 3.7 docs.  I don't feel any real need to backport it.

https://github.com/python/cpython/commit/9f74deba784fc8781d13ed564f69c02ed7c331bb

merged by Warsaw (last March).  It removed the whole phrase, "Instead of the normal %-based substitutions,"  I think the other changes would be more worth backporting, (assuming correct for 3.6, which I believe they are) if anything is.