What kind of systems are the traditional focus of phonology?
Phonology is a branch of linguistics concerned with the systematic organization of sounds in languages. It has traditionally focused largely on the study of the systems of phonemes in particular languages (and therefore used to be also called phonemics, or phonematics), but it may also cover any linguistic analysis either at a level beneath the word (including syllable, onset and rime, articulatory gestures, articulatory features, mora, etc.) or at all levels of language where sound is considered to be structured for conveying linguistic meaning. Phonology also includes the study of equivalent organizational systems in sign languages.
Brooke Foss Westcott (1825–1901) and Fenton J. A. Hort (1828–1892) published an edition of the New Testament in Greek in 1881. They proposed nine critical rules, including a version of Bengel's rule, "The reading is less likely to be original that shows a disposition to smooth away difficulties." They also argued that "Readings are approved or rejected by reason of the quality, and not the number, of their supporting witnesses", and that "The reading is to be preferred that most fitly explains the existence of the others."