=== spin lock offset ===
The offset is in the literature noted as $\Omega$, where $\Omega$ is the $^{15}$N resonance offset from the spin-lock carrier.
In the literature, the values are often stated as "offset", "carrier offset", "offset of the spin-lock pulse" with values given in Hz, and have values from 0-500 to 10-20.000 Hz.