Frank wrote --

> basically what you are saying is that moving text needs to keep information
> about its state with it, right? it fortunately doesn't need to keep
> information about its input encoding since that got all normalised into the
> internal representation but unfortunately you need to keep information about
> the encoding used (or rather the encoding intended)
> a bit inconsistent that, isn't it?

Not really: since input encoding really does mean just that.

Once the text is `inside LaTeX' the input encoding is irrelevant: that
is the beauty and strength of the LaTeX text character model.

The confusion perhaps comes because part of the `inside of LaTeX' is
various external files, .toc, .aux etc.  These are unfortunately not
internal to TeX, only to LaTeX.  The whole concept of `moving argument'
arises from this fundamental distinction between TeX and LaTeX: LaTeX,
in this sense, is not just a TeX macro package.

> but would it help if the language has a tie
> to the [font] encoding?

Whether the `intended font encoding' should be part of a moving
argument leads to an important question.

Note the word `intended': will it always be the case that text from a
moving argument should be turned into glyphs using the same font encoding
as was used for the original text?

> so we have to offer a choice, question is, is there a better way to present
> it?

This is not really an answer but we can certainly provide a better
interface than:

>  \usepackage[T1]{fontenc}

... no, I am not sure what it would be:-).