Clairnote DN's clefs simply indicate the octave register of the current staff. Unlike traditional clef signs, they do not change the notes that are represented by the lines and spaces of the staff. In Clairnote DN the lines and spaces always represent the same notes in each octave (see Staff). This simplification makes learning to read music easier. Piano players really benefit because in the traditional system they have to read music in both treble and bass clefs at the same time.
Here is the same note ("middle C" or "C4") shown in treble, bass, and alto clefs in both Clairnote DN and traditional notation. The resemblance between traditional clefs and Clairnote DN clefs makes it easier to learn to read both systems.
The numbers in the Clairnote DN clefs indicate the octave of the pair of staff lines nearest to the number. They follow the common numbering scheme for octaves. (Scientific pitch notation where an octave starts on C and extends up to B.) A higher or lower number in a clef indicates a higher or lower range/register on the staff. This is similar to transposed clefs in traditional music notation (also known as octave clefs), but it is easier to see at a glance which octave(s) the clefs signify.
Here is a series of clefs from low to high ranges, showing the note E in seven different octaves for both Clairnote DN clefs and traditional transposed clefs.
A Simpler Clef System
Clairnote DN's clef system simplifies the various different kinds of clefs found in traditional notation. When converting music from traditional notation to Clairnote DN, traditional clefs become the Clairnote DN clef that has the closest range (treble, bass, or alto, at a given octave register). This simplification is possible because Clairnote DN's clefs only indicate the octave register of the staff and do not change the notes on the staff lines and spaces.
The following image shows the clefs on the Clairnote DN staff that correspond to all of the different clefs on the traditional staff (french, treble, soprano, mezzosoprano, alto, tenor, baritone, varbaritone, bass, subbass, and percussion).
In the traditional system all of these different clefs allow for fine-tuning of the range of the staff for a particular instrument or voice range. However, this specialization makes it harder for musicians to read music that is written in different clefs. Is this trade-off worth it? Most of the traditional clefs shown above are now rarely used. That suggests that the added complexity they introduce may not be (or may no longer be) worth the benefits they offer.
Technically it would be possible to use the traditional treble, bass, and alto clef symbols with Clairnote DN (e.g. for their aesthetics). That is, as long as it was understood that they only represent octave registers and do not affect the notes represented by the lines and spaces of the staff. However, this could easily cause confusion, so it is best to use Clairnote DN's clef symbols, for consistency and to keep things clear and unambiguous.