What does zul stand for?

Zulu - MARC language code - Library of Congress (LCCP)

Agway, Inc., Library, Syracuse, NY - OCLC symbol (OCLC)

Silfi - Saudi Arabia - Airport symbol (AD)

Zirkel Und Lineal (TLAA)

Zulaica y Cia - NCIC firearms make code (NCIC)

Zurich-Lageren - Switzerland - Seismograph station code, US Geological Survey (SEIS)