What is considered "low frequency" for EM LF Simulations?

Hi, I'm wondering how low the frequency has to be to be considered "low frequency" in the EM LF Electro Simulations. At what frequency level (eg 1kHz, 10kHz, 100kHz, 1MHz?) does it become unreliable and we should use the EM FDTD instead? Is there a method for proving that a certain frequency is within the LF range (as justification for why this type of simulation was chosen)? Thanks!

See the Sim4Life Manual (2.6.1 EM LF  Simulation Theory)
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The quasistatic conditions are sufficient conditions for the quasistatic approximation to hold. In practice, there are cases where the quasistatic approximation still yields accurate results even when the quasistatic conditions are not satisfied. The guideline for this type of cases is to compare to results from fullwave simulations.
A table of the quasistatic approximation criteria for every simulation is written in the log file:
Solid settings: frequency = x Hz, characteristic length (worst case domain diagonal) x
Epsilon Mu SigmaE QS Approx. Quality Static Magn. Field SigmaE/wEpsilon Solid name
The column QS Approx. Quality and Static Magn. Field refers to quasistatic conditions. The column SigmaE/wEpsilon indicates whether the displacement current ( â‰ª1 ) or the ohmic current dominates ( â‰«1 ).2.6.1.4 Choosing the Appropriate Low Frequency Solver has further details