The pattern string to use in this message formatter.
The pattern uses an 'apostrophe-friendly' syntax; it is run through
» umsg_autoQuoteApostrophe
before being interpreted.
Default pattern: '{0,number} monkeys on {1,number} trees'
Formatting result: 123 monkeys on 456 trees
New pattern: '{0,number} trees hosting {1,number} monkeys'
Formatted number: 123 trees hosting 456 monkeys