ITU-T G.652A

attributes, contains the recommended attributes and values needed to support applications such as those recommended in [ITU-T G.957] and [ITU-T G.691]
up to STM-16, as well as 10 Gbit/s up to 40 km (Ethernet) and STM-256 for [ITU-T G.693].

ITU-T G.652B

attributes, contains recommended attributes and values needed to support higher bit rate applications, up to STM-64, such as some in [ITU-T G.691] and [ITU-T G.692], STM-256
for some applications in [ITU-T G.693] and [ITU-T G.959.1]. Depending on the application, chromatic dispersion accommodation may be necessary.

ITU-T G.652C

attributes, is similar to ITU-T G.652.A, but allows transmissions in portions of an extended wavelength range from 1360 nm to 1530 nm.

ITU-T G.652D

attributes, is similar to ITU-T G.652.B, but allows transmissions in portions of an extended wavelength range from 1360 nm to 1530 nm.