Among my various 45 ACP cases are a few of Israeli manufacture, with either IMI or TZZ at the 12 o'clock position, the date at 6 o'clock and a pair of dots like a colon ( at 3 o'clock. At 9'oclock is either a single dot or a colon. Any significance to this variation?

Bud W

IIRC it's a coding that indicates which station it went through on the automated loading presses.
They obtained surplus loading equipment from the US, which held something like 20 rounds at a time (all 20 went through the steps at the same time). Each of the 20 stations had a different "dot" code location/combination