Lists a GTM container's VERSION HISTORY (newest first) and marks which one is currently LIVE. Each version is a published snapshot — use this to see what changed and when, or to pick a version to roll back to with rollback_gtm_version. container = 'GTM-XXXX'/name (empty if only one). DATES: the newest details versions (default 10, max 25, 0 = off) also carry saved_at (when the version was created/saved, UTC) and description (the change notes typed at publish time). Use them to answer 'what changed between date X and Y'. Google's API does not expose who published a version — that is only visible in the GTM web UI.