str.istitle(): Return True if the string is a titlecased string and there is at least one character, for example uppercase characters may only follow uncased characters and lowercase characters only cased ones. Return False otherwise.

I saw this description from the doc. But what does "cased" andd "uncased" mean? I looked it up on a dictionary, and the latter only says: "cased in something: completely covered with a particular material".

I think "cased" may be "capitalized", but, if so, the usage of the former is not endorsed by dictionaries so that I think this word is confusing or informal. so does "uncased".

"Cased": Characters which are either lowercase or uppercase (they have some other equivalent form in a different case)

"Uncased": Characters which are neither uppercase nor lowercase.

Do you have a suggested alternate wording?

Why does "a".istitle() return "False" while it is not followed by any uncased character?

See the docs for the title method on what they mean by "titlecased"; "a" is self-evidently not titlecased. https://docs.python.org/3/library/stdtypes.html#str.title

FWIW, the current terminology is confusing to me as well.

@ Josh Rosenberg Sorry, I mistook "follow" as "be followed by". Thanks to your explication, the document is coherent. I admit that I cannot conjure up any better altnernative.

I noticed that "cased character" are explained via the footnote: https://docs.python.org/3/library/stdtypes.html?highlight=istitle#id6

So it may be better to add a footnote for "uncased characters" as well, like ones in "str.istitle()" and "str.upper()".

By the way, the footnote for "cased character" is a bit confusing because of the curt abbreviations "Lu", "Ll", and "Lt". I did not get these until I fount out they are related to general category of unicode, so we could add a related link pointing to a related Unicode document.

Or we could integrate the explanation of uncased characters into the footnote for cased characters, and append the footnote in "str.istitle()" and "str.upper()".

I've put up a PR that adds a footnote, clarifies 'uncased' meaning and also adds notes in regard to discrepancy between standard publishing definition of "title case" and what we use in the four title-related methods.