To keep track of what the default natural language is.

§1. The following mechanism may become more sophisticated later.

NATURAL_LANGUAGE_WORDS_TYPE *default_language_for_linguistics = NULL;

void DefaultLanguage::set(NATURAL_LANGUAGE_WORDS_TYPE *nl) {
    default_language_for_linguistics = nl;
}

NATURAL_LANGUAGE_WORDS_TYPE *DefaultLanguage::get?Usage of DefaultLanguage::get:
Article Inflection - §1
Grading Adjectives - §2, §3, §4
Past Participles - §2
Pluralisation - §3, §4
Lexical Clusters - §3, §4, §4.1.1
Declensions - §5, §6, §8
Verb Conjugation - §6, §7.2.1, §17(NATURAL_LANGUAGE_WORDS_TYPE *nl) {
    if (nl) return nl;
    return default_language_for_linguistics;
}