### The Problem

Using native Qt translation files (TS, `*.ts`) for exchanging with Transifex platform limits means to provide context
to translators to the only category:

| C++ source code                               | TS XML element                                 | Transifex metadata
|-----------------------------------------------|------------------------------------------------|:------------------:
| Class Name                                    | `<name>`ClassName`</name>`                     | Context
| `disambiguation` parameter of `tr()` function | `<comment>`Short comment`</comment>`           | N/A
| [Translator Comments](https://doc.qt.io/qt-5/i18n-source-translation.html#translator-comments) `//: ...` | `<extracomment>`Nice comment.`</extracomment>` | N/A

More details:
- https://docs.transifex.com/formats/introduction
- https://docs.transifex.com/formats/qt-ts
- https://doc.qt.io/qt-5/linguist-ts-file-format.html

### The Solution

[XLIFF](https://en.wikipedia.org/wiki/XLIFF) file format is supported by Transifex much better.

And Qt provides us with a stand-alone conversion tool `lconvert`.

```sh
$ lconvert -o bitcoin_es.xlf -i bitcoin_en.ts
```

Now more context options are available:

| TS XML element                                 | XLIFF XML element                               | Transifex metadata
|------------------------------------------------|-------------------------------------------------|:------------------:
| `<name>`ClassName`</name>`                     | `<group resname="ClassName">`...`</group>`      | yes
| `<comment>`Short comment`</comment>`           | `<context>`Short comment`</context>`            | yes
| `<extracomment>`Nice comment.`</extracomment>` | `<note from="developer">`Nice comment.`</note>` | yes

More details:
- https://docs.transifex.com/formats/xliff
- https://code.qt.io/cgit/qt/qttools.git/tree/src/linguist/lconvert/lconvert.pro?h=5.12.10

---

Looking for Concept (N)ACKs.
"The block database contains a block which appears to be from the future. "
"This may be due to your computer's date and time being set incorrectly. Only "
"rebuild the block database if you are sure that your computer's date and "
"time are correct"),
QT_TRANSLATE_NOOP("bitcoin-core", ""
"The transaction amount is too small to send after the fee has been deducted"),
QT_TRANSLATE_NOOP("bitcoin-core", ""
"This error could occur if this wallet was not shutdown cleanly and was last "
"loaded using a build with a newer version of Berkeley DB. If so, please use "
"the software that last loaded this wallet"),
QT_TRANSLATE_NOOP("bitcoin-core", ""
"This is a pre-release test build - use at your own risk - do not use for "
"mining or merchant applications"),
QT_TRANSLATE_NOOP("bitcoin-core", ""
"This is the maximum transaction fee you pay (in addition to the normal fee) "
"to prioritize partial spend avoidance over regular coin selection."),
QT_TRANSLATE_NOOP("bitcoin-core", ""
"This is the transaction fee you may discard if change is smaller than dust "
"at this level"),
QT_TRANSLATE_NOOP("bitcoin-core", ""
"This is the transaction fee you may pay when fee estimates are not available."),
QT_TRANSLATE_NOOP("bitcoin-core", ""
"Total length of network version string (%i) exceeds maximum length (%i). "
"Reduce the number or size of uacomments."),
QT_TRANSLATE_NOOP("bitcoin-core", ""
"Transaction needs a change address, but we can't generate it. Please call "
"keypoolrefill first."),
QT_TRANSLATE_NOOP("bitcoin-core", ""
"Unable to replay blocks. You will need to rebuild the database using -"
"reindex-chainstate."),