Z5

The z5 file extension is associated with Infocom and used for files that contain Z-machine instructions (called story files, or Z-code files). Z-code files usually have names ending in .z1, .z2, .z3, .z4, .z5, .z6, .z7 or .z8 (and occasionally .dat), where the number is the version number of the Z-machine on which the file is intended to be running.

Types 1, 2, 4, 6, and 7 are extremely uncommon; most Z-machine data files are types 3, 5, or 8. Type 6 provides some graphics support.

Interpreters for Z-code files are available on a wide variety of platforms - on various old machines (such as the Apple II, TRS-80 and Sinclair), portable machines (such as Palm OS devices and the Nintendo Game Boy) and most modern platforms.

The Z5 file extension is associated with ZoneAlarm, a personal firewall software, originally created by Zone Labs and currently developed by CheckPoint Software Technologies LTD.

One of ZoneAlarm features is MailSafe, which detects e-mail attachments and warns the user about their presence. When a potentially dangerous attachment is detected, the program quarantines the file with simple renaming of its original file extension, so it breaks the common program association function in Windows and prevents such files from being executed (or launched via associated program).

A file with Z5 file extension had its original file extension renamed for security reasons.