This read-only INTEGER value (in ps/nm) reports the Chromatic Dispersion currently measured on the coherent optical channel (och-os) on the line side of a pluggable transceiver. An administrator watches this value to confirm the coherent receiver's dispersion compensation is tracking correctly and to sanity-check it against the expected dispersion for the known fiber distance and type. For example, an unexpectedly large chromatic dispersion reading on och-os compared to what the fiber route's length would predict might indicate the signal is actually traversing a longer or different physical path than assumed.