Symbol Names: None, this is placed as text on the schematic.
Syntax: Kxxx L1 L2 [L3 ...] <coefficient>
L1 and L2 are the names of inductors in the circuit. The mutual coupling coefficient must be in the range of -1 to 1.
The line
K1 L1 L2 L3 L4 1.
is synonymous with the six lines
K1 L1 L2 1.
K2 L2 L3 1.
K3 L3 L4 1.
K4 L1 L3 1.
K5 L2 L4 1.
K6 L1 L4 1.
It is recommended to start with a mutual coupling coefficient equal to 1. This will eliminate leakage inductance that can ring at extremely high frequencies if damping is not supplied and slow the simulation. However, a mutual inductance value of -1 or 1 can lead to simulation difficulties if the uic directive is flagged on the .tran card.