Why isn't ARFCN 0 supported?

Good afternoon! In libbsc/bsc_init.c we have the following case: case GSM_BAND_900: if (bts->c0->arfcn < 1 || (bts->c0->arfcn > 124 && bts->c0->arfcn < 955) || bts->c0->arfcn > 1023) { LOGP(DNM, LOGL_ERROR, "GSM900 channel must be between 1-124, 955-1023.\n"); return -EINVAL; } break; 3GPP 45.005, table 2-2 gives valid channel numbers as: P-GSM900 -> 1-124, E-GSM900 -> 0-124 and 975-1023 R-GSM900 -> 0-124 and 955-1023 ER-GSM900 -> 0-124 and 940-1023 The code looks to bounds check ARFCN closest to R-GSM900, but omits ARFCN 0. Is the check "bts->c0->arfcn < 1" erroneous, or am I missing some history? Also should it really check for the R-GSM 900 range, or should it be E-GSM (more common)? The other band checks look correct. Kind Regards, Mike PS: osmo-arfcn is okay with ARFCN 0: $ ./osmo-arfcn -a 0 ARFCN 0: Uplink 890.0 MHz / Downlink 935.0 MHz