Most of what you record about an excavation unit is structured — its unitDesignation, unitType, the dimensionNS and dimensionEW measurements, the datumElevation, the running currentDepth, and its status. The notes field is where everything else goes: a description of unexpected soil conditions, why digging paused, how the unit relates to an adjacent one, or a reminder for whoever opens the unit next. Because it is optional and unconstrained, it is the natural place for the narrative detail that makes a unit understandable months later when you are writing up the site. Good notes turn a row of measurements into a story a reader can follow.
Technical section
Data model, API, and internals — visible to developers.