Collation Strength
The setStrength() method determines the number of collation strength levels taken into consideration by RWUCollator. For example, setting a collator’s strength to RWUCollator::Primary causes it to ignore secondary and tertiary differences in collation weights, in effect ignoring diacritical and case differences.
Quaternary strength is useful only in two situations:
When punctuation shifting is enabled (Punctuation Shifting), whitespace and punctuation characters are ignored at the first three strength levels, and are distinguished at the quaternary level.For Japanese locales, hiragana characters are positioned before katakana characters at the quaternary level, mimicking JIS sort order.The default strength level for most locales is tertiary; for Japanese, it is quaternary.
The getStrength() method returns the current collation strength associated with the collator.
