structural:summarization, information:extraction
Collation

Some modified letters, such as the symbols ⟨ å ⟩, ⟨ ä ⟩, and ⟨ ö ⟩, may be regarded as new individual letters in themselves, and assigned a specific place in the alphabet for collation purposes, separate from that of the letter on which they are based, as is done in Swedish. In other cases, such as with ⟨ ä ⟩, ⟨ ö ⟩, ⟨ ü ⟩ in German, this is not done; letter-diacritic combinations being identified with their base letter. The same applies to digraphs and trigraphs. Different diacritics may be treated differently in collation within a single language. For example, in Spanish, the character ⟨ ñ ⟩ is considered a letter, and sorted between ⟨ n ⟩ and ⟨ o ⟩ in dictionaries, but the accented vowels ⟨ á ⟩, ⟨ é ⟩, ⟨ í ⟩, ⟨ ó ⟩, ⟨ ú ⟩, ⟨ ü ⟩ are not separated from the unaccented vowels ⟨ a ⟩, ⟨ e ⟩, ⟨ i ⟩, ⟨ o ⟩, ⟨ u ⟩.