Each line represents a single note. May be stacked for polyphony. An integer represents a relative note on the 12 tone chromatic scale. An absolute frequency reference may be represented anywhere (usually at the beginning of a piece) with the notation of fix '0' = 440 Hz. From that point on all notes are interpreted as N * 2^(1/12), where 'N' is the integer being interpreted. Every note is a whole note (a single note per beat). Fractional notes may be represented in parenthesis where the contents of the entire parenthesis in a single beat. So half notes would be (0,0) and quarter notes (0,0,0,0).
The duration (pulse width) of the note is not necessarily part of it's beat length. But default the duration of a note is assumed from context. Play what seems correct. To be explicit in note length use notation N^Bf where N is the note integer and Bf is the beat factor multiplier. For example, the following is valid yet it is impossible to play on a piano:
fix '0' = 440 Hz 0 (0^1, 0^1, 0^1, 0^1)
The first whole note 0 is played. Then four more 0 notes are sounded in 1/4 time beat, but with a duration equal to a full beat. In the real world this is impossible to play on most instruments. If you had four pianos you could play the A4 (middle concert A). This implies that spaces between notes are implied (yes, implication can be implicated).
There should be a difference notation for "fix". One operator should reset all notes relatives to the given frequency. It should be implied that we are resetting all relative to '0'. A second operator should allow fixing some notes as absolutes without respect to the current baseline frequency. This may be a bad idea. The whole motive for using numbers is to imply the relative nature of the notes. If we need something else then perhaps we use other symbols or just specify an absolute frequency or a sound clip to play.