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Current behavior
Currently, the ID of messages to translate are generated based on the content of the element with the i18n attribute.
This is extremely painful and causes several problems:

• as soon as the content is modified or simply reformatted (like for example simply adding a meaningless line break), the ID changes and all the message files must be impacted
• some contents might be identical in the base language, but have a different translation in other languages (for example, "free" might mean "free as in speech" or "free as in beer", and other languages have different words for that)
• some contents can be identical in two different contexts in the base language, but need to be have different translations in other languages to avoid potential ambiguities.

Expected behavior

It would be much easier to maintain if the developer could simply choose the ID (as an optional additional feature):

    <span i18n i18n-id="home.freeAsInBeer">Free</span>
    <span i18n i18n-id="home.freeAsInSpeech">Free</span>

and if the extraction tool honored the chosen ID instead of generating one:

      <trans-unit id="home.freeAsInBeer" datatype="html">
        <source>Free</source>
        <target/>
      </trans-unit>

      <trans-unit id="home.freeAsInSpeech" datatype="html">
        <source>Free</source>
        <target/>
      </trans-unit>

Or if the ID was computed based on the value of the i18n attribute if present, rather than based on the content of the element.

What is the motivation / use case for changing the behavior?
Avoid having to constantly change the IDs in all the message files when the message is just reformatted or slightly changed. Make it simpler to specify two different translation units even if the base content is identical.

Please tell us about your environment:

OSX Sierra

• Angular version: 2.0.X
  2.4.1

• Browser: NA

• Language: TypeScript 2.0.10

• Node (for AoT issues): node --version = 6.9.2