DOC is acronym of document, or documentation, or documentaries, first of all, if you are going to ship a container, there would be miscellaneous files come and go which whose provided by shipper, forwarder, carrier...etc. before shipping a container a booking form must submit to carrier to have it confirmed, then get SO, shipping order.
as long as the container returned to port, then into customs declaration process, once done it, the customs release note will hand over to carrier, then port will crane the container to vessel according to the right voyager. after done the port works. the shipper, forwarder, carrier should confirm a series information, such as shipper's info, consignee info, cargo list, weight, cubic meter of the goods, bill of lading double check.
DOC fee rate
Different port, different carrier charge different cost, since then, a common recognized cost for DOC as following
2009 before about 200RMB
2012 after about 300RMB
2015 after about 400RMB
2017 since to now about 500RMB
if you got big volume to container, such as more than 100 pcs a month, you can apply SO direct from carrier company, and discuss DOC fee and THC handling fee, only several container needs to ship, ask forwarder to handle is most convenient