It is not a consumer file compression software like WinZip or 7-Zip. Instead, it refers to the associated with specific research "Cohorts." Technical Definition
: The name typically stands for "Cohort 18 Baseline ZIP Code" . B18zip
: You may see it alongside other coded fields like F18PBPID (Plan Benefit Package ID) or STATE in the HOS Data User’s Guide . It is not a consumer file compression software
"B18zip" is a specific data field label used in medical health research datasets, most notably in the documentation . most notably in the documentation .