Tablature (TAB) has been used for a lot of the notation so that no one is restricted by their level of sight reading proficiency. Each string is represented by a line and the numbers refer to fret numbers. For example, a C note which is on the third fret on the A string would be notated as:

A dual Bass clef / TAB format has been used throughout most of enable Bass.

Some bass lines contain additional information. The letters stand for:

x Ghost note
H Hammer on
P Pull off (PO is used when there is also P for pop in the same piece of music)
T Thumb (slap)
P Pop (slap)