Every port used in international trade has a five character UN/LOCODE. Tuzla is TR TZL. Knowing the format prevents the most common data entry error in agency and customs paperwork.
How the code is built
A UN/LOCODE has two parts: a two letter country code set by ISO 3166, followed by a three letter location code assigned by the UN Centre for Trade Facilitation and Electronic Business. For Turkey the country prefix is always TR, so every Turkish port code starts the same way and differs only in the three letter suffix.
Tuzla is TR TZL, Ambarli is TR AMB, and Aliaga is TR ALI. The pattern is consistent enough that once the logic is understood, guessing the suffix for an unfamiliar port and then confirming it against the official UN list is usually faster than searching from scratch.
Where the code is actually used
Shipping software, customs declaration systems, and port community systems all reference UN/LOCODE rather than a port's full name, because the code is unambiguous across languages and spelling variants. A port agency instruction that carries the wrong code, even with the correct port name written alongside it, can cause a system-level mismatch that a human reader would never catch by eye.
This is why the code deserves its own line in any agency instruction or customs document, checked against the official list rather than copied from memory or a previous, possibly outdated, document.
A short list of the ports Yeke works most
Tuzla (TR TZL), Ambarli (TR AMB), Aliaga (TR ALI), Izmit (TR IZT), and Gemlik (TR GEM) cover the bulk of the traffic Yeke Denizcilik handles day to day, and having these five memorised removes the lookup step for most routine agency and customs work.