Upgrading 1password on one machine change data file format, making it incompatible with old version?

I have a work laptop that is El Capitan, and I was wondering if I upgrade the application if the data file format changes, making it incompatible with other older (e.g., Snow Leopard, Mountain Lion) clients syncing with the data file via dropbox.

@drjmetz: Thanks for reaching out. Great question! The short answer is that all versions of 1Password going back to Tiger (yeah, way back) can use the AgileKeychain format. So if your vault in Dropbox is called 1Password.agilekeychain or similar, you're all set.

However, though you specifically mentioned Snow Leopard, I do want to raise one caveat: since 1Password 3 (on Snow Leopard and Lion) does not understand some of the newer data used by 1Password 4 and later, be sure to use 1Password 3 only to read the vault; do not make changes to a vault with 1Password 3 if you'll be using it with 1Password 4 or later, as it can result in some item data being inaccessible to the other apps (even though it is still present).

I hope this helps. Be sure to let me know if you have any other questions! :)