Glossary - alphabet order - "N"
This is the resistance value of the crystal oscillation circuit, from the perspective of the crystal unit. As such, it is one of the parameters that indicate the oscillation characteristics of the crystal oscillation circuit. It is called "negative" resistance because energy is generated rather than consumed.
Relation be tween crystal unit
and crystal oscllation circuit
The nominal frequency is the oscillation frequency of a crystal unit with a specified load circuit. Frequency variation of the oscillation depends on the amount of load applied to the crystal oscillation circuit, so "nominal" is attached as an adjective to indicate the oscillation frequency of a crystal unit with a specified load circuit.