Port of loading is the named port where goods are loaded aboard the vessel, entered as a field on the bill of lading or sea waybill. Its meaning comes from the contract of carriage and the document itself: the field records a fact about the carriage, and the legal weight it carries depends on the sale terms sitting alongside it. Under some terms of sale risk and cost pass at this point; under others they do not. It is not the same as place of receipt, which may be inland and earlier. Where the two differ, check which one the sale contract and any documentary credit actually key to — the mismatch is a common cause of rejected documents.
Why this entry carries no source list. This lexicon cites an official primary source wherever one exists and says so plainly where none does. This term is market convention: it was coined by commercial practice, it is used by everyone in the trade, and no body defines it. Pointing at a carrier’s tariff, a bank’s product page or a trade association’s explainer would dress one participant’s usage as a general rule. The practical upshot runs through the paragraph above — where the word carries no fixed meaning, the contract has to supply one.