Persistent spectral holes in amorphous systems can remain sharp and may display a linear shift upon the variation of the external magnetic field when they are burned in high fields. Experiments were performed on the R line of [Cr(NCS)(6)](3-) in glycerol at 4.2 K. When the spectral hole is burned in a field of 3.2 T it displays a linear shift of 26.4 GHz/T upon the variation of the magnetic field strength from 2.8 to 3.6 T. The shift corresponds to an average excited-state R-value of 2.17. The broadening of the hole implies an upper limit of the anisotropy and/or strain of the excited g-value of approximate to 15%. The linear shift can be used to read out the spectral hole by sweeping the magnetic field.