Multi-lingual Content filter
From MoodleDocs
multilangsecond project is a Moodle filter. It is a more flexible version of multilang filter. It has an admin setting filter_multilangsecond_mode. If this setting is set to 'Yes' non html syntax can be used for multilang blocks like
{mlang en}English{mlang}{mlang bg}Bulgarian{mlang}
Otherwise language block is a serie of identical html tags with lang="XX" atributes:
Heading in English
Heading in Bulgarian
or
Paragraph in English
Paragraph in Bulgarian
Paragraph in Romanian
The old syntax with <lang> tags is valid too.