Reusing DX coced cassettes

If I reload a DX cassette that was coded for 36 exposures with a shorter length (12-18-24 exp), will the camera rewind after the last exposure, or does it wait for the DX 36th exp? Is it the coding, or the tension of the filmed spooled to the end, that starts the rewind sequence?
Gerry

Very few cameras use the film length information from the DX code. How many rows of contacts does your camera have? If there's only one row, then it can't read the length.
If it does read the film length DX info, then the rewind sequence is triggered by either DX or tension - whichever comes first. At least that's how my EOS 1V used to work. So you'll have no problems loading 24 exposures into a 36-exposure cassette, but it may not work the other way around.

Vlad,
Thanks for your info. Mine has 1 row of 4 contacts, so I should be OK.