Stem and slur notation is an analytical means of depicting melodic and harmonic relationships in music.
As its name suggests, at its core, stem and slur notation comprises stemmed and unstemmed notes which, depending on their analytical significance, are connected by slurs.
Stemmed notes typically indicate a note, chord or larger section which is tonally important. This can be seen at its most basic in the following excerpt where harmony notes are stemmed while non-harmony notes are unstemmed and are connected by slurs to stemmed notes.
The connection may be at a ‘local’ level, as in the previous example, where the passing and neighbour notes are slurred directly to harmony notes – notice, there may be more than one note slurred to a stemmed note, or the connection may be across a larger section of music, as in the following example, where the slurred C note (shown by the arrow) indicates a connection across several bars – showing that the C major harmony is continued through these bars.
In this example also, notice that often with stem and slur notation the musical texture is reduced: the repeated E notes in the treble clef are in the analysis represented by a single stemmed note to which others are slurred.
At a ‘higher’ level of analysis, the first three bars of this example could be reduced further showing the prolonged C major harmony as a single quarter note beat moving to D minor harmony.