indicate language sensitivity in autocapitalization

[aphillips]

The autocapitalization attribute (found here, currently section 6.6.6) describes handling of the hint to virtual keyboards and voice input systems for the handling of bicameral scripts (that is, for scripts that have an upper and lower case). I18N and HTML previously discussed the wording in this section. We are revisiting this to make a few more editorial suggestions to improve understanding of the text. Please advise if you would prefer a PR for this.

Primarily, our concern is that not enough emphasis is put on the language-specific behavior of the affected keyboard/input system. That is, it is the language of the keyboard that controls what the hint "means". We suggest the following edits:

1. Introduce the concept at the start of the section by inserting text along the lines of:

A few languages and writing systems distinguish between upper, lower, and titlecase letters.

2. Introduce additional clarification after this sentence in the second paragraph:

The autocapitalize attribute, as typically implemented, does not affect behavior when typing on a physical keyboard. (For this reason, as well as the ability for users to override the autocapitalization behavior in some cases or edit the text after initial input, the attribute must not be relied on for any sort of input validation.)

Saying something akin to:

Virtual keyboards or other input systems normally interpret the attribute in a script or language-specific manner. In some languages, the hints are ignored or receive special treatment.

This is especially true for a few languages (Cherokee, Georgian) that have added lower or upper case letters (respectively) for specific local or historical needs, as well as the general complexity of bicameral scripts. I don't think it is necessary to spell out all of this in HTML. We do address this to some degree in Charmod-Norm, although not directly.

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This issue was discussed in the I18N teleconference on 2019-04-11, when we re-examined progress on our original issue. That issue has been addressed: thank you. I was actioned to create this issue.

[domenic]

This all makes sense to me! A pull request would be lovely.