Which acquisition band can be selected is determined by the broadband source that is being used at the far end. SCL is the standard band (1460-1625nm) and can be used with various modulated broadband light sources. OESCL is the full band (1260-1640nm) and only available on certain broadband source types such as the BBS2A. The OBS500, OBS550 or the BBS1A sources would use the SCL setting.