What do the exclamation marks in Rails i18N translation yml file mean?

Question

I'm using Rails i18n to localize my website.

In the translation yml file, I see

time:
    am: am
    formats:
      default: ! '%a, %d %b %Y %H:%M:%S %z'
      long: ! '%d %B, %Y %H:%M'
      short: ! '%d %b %H:%M'
    pm: pm

(taken from https://github.com/svenfuchs/rails-i18n/blob/master/rails/locale/en-GB.yml)

What does the exclamation mark mean? How is it different if you take away the exclamation mark?

Thanks

Answer 1

% is a special character in YAML. Single exclamation mark avoids it to be parsed as a special character and passes it as a String.

Answer 2

Copying the answer from the comments in order to remove this question from the "Unanswered" filter:

See What does a single exclamation mark do in YAML?

~ link per Stefan, linked question answered by Juan Mellado