For a fixed VLRBW = 200 kHz, and fixed ItBW= 200 kHz, the attenuation Att(dBc/Bref) will be different depending on the values of the Bref in order to achieve the same interference power level.
Case 1, ItBW > Bref :
Bref = 100 kHz, with Att = -3 dBc/Bref, iRSS = -51.48 dBm;
As mentioned in Section A7.5 on p.287, if the reference bandwidth is lower than the emission bandwidth then the attenuation must be defined with negative sign;
Case 2, ItBW = Bref:
Bref = 200 kHz, with Att = 0 dBc/Bref, iRSS = -54.49 dBm;
If the reference bandwidth is equal to the emission bandwidth then the attenuation should be set as zero.
Case 3, ItBW < Bref:
Bref = 400 kHz, with Att = 3 dBc/Bref, iRSS = -57.5 dBm;
If the reference bandwidth is larger than the emission bandwidth then the attenuation must be defined with positive sign;