A voice type is a particular human singing voice identified as having certain qualities or characteristics of vocal range, vocal weight, tessitura, vocal timbre, and vocal transition points (passaggio), such as breaks and lifts within the voice. Other considerations are physical characteristics, speech level, scientific testing, and vocal register. A singer's voice type is identified by a process known as voice classification, by which the human voice is evaluated and thereby designated into a particular voice type. The discipline of voice classification developed within European classical music and is not generally applicable to other forms of singing. Voice classification is often used within opera to associate possible roles with potential voices. Several different voice classification systems are available to identify voice types, including the German Fach system and the choral music system among many others; no system is universally applied or accepted.