Port

Talking about transport infrastructure, ports include river ports. direct historical or archaeological evidence of ports is absent when no port has been excavated or all evidence of such has been obliterated. indirect historical or archaeological data is absent when there is no evidence that suggests that the polity engaged in maritime or riverine trade, conflict, or transportation, such as evidence of merchant shipping, administrative records of customs duties, or evidence that at the same period of time a trading relation in the region had a port (for example, due to natural processes, there is little evidence of ancient ports in delta egypt at a time we know there was a timber trade with the levant). when evidence for the variable itself is available the code is 'present.' when other forms of evidence suggests the existence of the variable (or not) the code may be 'inferred present' (or 'inferred absent'). when indirect evidence is not available the code will be either absent, temporal uncertainty, suspected unknown, or unknown.   (See here)