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If one translates a sentence that has a tag, the tag gets "lost" i.e. One doesnt see it next to the translated sentence. I think the tags of a sentence should be displayed just like the sentences themselves: the tags of the sentence youre looking at in colour and the ones of the translations greyed out (or similar). Like this these tags could get shortcuts to add the same tag to the current sentence and (even more important) work as a kind of annotation.
E.g. if the tag next to a translation says "rude" I would rather not use it in a letter.
Would this be a good idea for the upcoming version? What do you think?
I think this makes sense for some tags, but not for others. For example "です。", "6 syllables", and "Spain Spanish" shouldn't be showing up on translations.
On the other hand, something like "weather", "family", or "romance" probably could apply to translations.
Theoretically, the system could keep a list of tags that were okay to apply to translations automatically, but I don't think it's really a necessary feature.
What I would like to see a lot more is a system for adding metadata. It would be like tags, except that the tag would store data. For example rather than having "by Albert Einstein" and "by Mark Twain", we would have a data-tag "by" and sentences could have "by: Albert Einstein" and "by: Mark Twain". A better example might be replacing "8 to 10 words" etc. with "number of words: 9" etc. Then the search function could let you, for example, find all the English sentences with between 12 and 19 words. The system could also be automated so we didn't have to sit there counting words. :-)
Sorry, i didnt point this out clear enough: I wouldnt want to automatically copy the tags, but just have the option to quickly do so. This means that there could be "spain spanish" next to the spanish translation of the current sentence (which wouldnt make much sence to click on unless the current sentence is also spanish). But if there would be written "family" next to the spanish sentnce and the current sentence also refers to something about "family" you might decide to click it and thereby quickly add this tag to the current sentence too.
As far as I see, not much "filter" needed
This would also add an oportunity to allow adding these tags for not-yet "trusted users": They would just click the tag from the oher sentence, without the possibility to mess things up.
Also I like your metadata-idea - lets see how sysko is going to solve this.
As for necessity: i think this might promote the usage of tags.